m 




COMPRISING 



V. 



INSTRUCTIONS IfS- THE SELECTION AND 

PREPiRATION OF DRAWING 

INSTRUMENTS, 



ELEMENTARY INSTRUCTION IN PRACTICAL 
MECHAMCAL DRAWING; 

TOGETHER AVITH 

EXAMPLES IN SIMPLE GEOMETRY AND ELEMENTARY MECH- 
ANISM, INCLUDING SCREW THREADS, GEAR WHEELS, 
MECHANICAL MOTIONS, ENGINES AND BOILERS. 

BY JOSHUA ROSE, M.E, 

AUTfiOR OF "the complete PRACTICAL MACHINIST,'* 
"the PATTERN MAKER's ASSISTANT," 

"the slide valve." 



8LLUSTRATED BY THREE HUNDRED AND THIRTY ENGRAVIN 



PHILADELPHIA: 
HENRY CAREY BAIRD & CO., 

INDUSTRIAL PUBLISHERS, BOOKSELLERS AND IMPORTERS; 
8io WALNUT STREET. 

LONDON : 

SAMPSON LOW, MARSTON, SEARLE & RIVINGTON, 




CROWN BUILDINGS, 



FLEET STREET. 



I Copyright by 

I joshuaRose. 

' 1883. 



h 



PHILADELPHIA: 
( OLLINS. PUINTKK. 



PREFACE. 



npHE object of this book is to enable the beginner to learn to 
■*• make simple mechanical drawings without the aid of an in- 
structor, and to create an interest in the subject by giving examples 
such as the machinist meets with in his every-day workshop practice. 
The plan of representing in many examples the pencil lines, and 
numbering the order in which they are marked, the author believe? 
to possess great advantages for the learner, since it is the producing 
of the pencil lines that really proves the study, the inking in being 
merely a curtailed repetition of the pencilling. Similarly when 
the drawing of a piece, such, for example, as a fully developed 
screw thread, is shown fully developed from end to end, even though 
the pencil lines were all shown, yet the process of construction will 
be less clear than if the process of development be shown gradually 
along the drawing. Thus beginning at an end of the example the 
first pencil lines only may be shown, and as the pencilling pro- 
gresses to the right-hand, the development may progress so that 
at the other or left-hand end, the finished inked in and shaded 
thread may be shown, and between these two ends will be found a 
part showing each stage of development of the thread, all the lines 
being numbered in the order in which they were marked. This 
prevents a confusion of lines, and makes it more easy to follow or 

to copy the drawing. 

(iii) 



iv PREFACE. 

It is the numerous inquiries from working machinists for a book of 
this kind that have led the author to its production, which he hopes 
and believes will meet the want thus indicated, giving to the learner 
a sufficiently practical knowledge of mechanical drawing to enable 
him to proceed further by copying such drawings as he may be 
able to obtain, or by the aid of some of the more expensive and 
elaborate books already published on the subject. 

He believes that in learning mechanical drawing without the aid 
of an instructor the chief difficulty is overcome when the learner 
has become sufficiently familiar with the instruments to be enabled 
to use them without hesitation or difficulty, and it is to attain this 
end that the chapter on plotting mechanical motions and the suc- 
ceeding examples have been introduced ; these forming studies that 
are easily followed by the beginner, while sufficiently interesting to 
afford to the student pleasure as well as profit. 

New York, February, 1883. 



CONTENTS. 



CHAPTER I. 

THE DRAWING BOARD. 

The T square .' l8 

The triangles = 19 

Curves 21 

Selecting and testing drawing instruments 22 

Lead pencils 23 

Mixing India ink 25 

The drawing paper 26 

Tracing paper , . . 29 

The ink 30 

Testing and selecting India ink 30 

Draftsmen's measuring rules ^^ 

CHAPTER II. 

THE PREPARATION AND USE OF THE INSTRUMENTS. 

Preparing the lining pen for use ; . . 34 

The shapes of the lining pen points 35 

Oilstoning pen points '..... 36 

Preparing the circle pen for use 38 

The shape for circle pen points 38 

Shaping circle pens for very small circles 39 

A form of pen point recently introduced ; forming the pen p>oint 39 

The method of oilstoning circle pen points 40 

(v) 



yj CONTENTS. 

The needle point and pen point 42 

How to use the circle pen 43 

German instrument to avoid slipping of a needle point 44 

How to use the lining pen 45 

Applying the ink to the bow-pen 46 

Using a straight line or lining pen with a T square 47 

CHAPTER III. 
LINES AND CURVES. 

Explanation of simple geometrical terms ; radius ; explanation of conven- 
tional dotted lines 48 

A line at a right angle to another; a point; parallel lines 49 

A line produced ; a line bisected ; a line bounding a circle ; an arc of a 
circle; segments of a circle; th-e chord of an arc; a quadrant of a 

circle ... 5c 

A sector of a circle ; a line tangent to a circle ; a semi-circle ; centre of a 
circle; axis of a cylinder; to draw a circle that shall pass through three 

given points 51 

To find the centre from which an arc of a circle has been struck ; the 

degrees of a circle 52 

The protractor 53 

To find the angle of one line to another. 5^ 

To find the angles of three lines one to the other.. 55 

Acute angles and obtuse angles 57 

Triangles ; right angle triangle ; obtuse angle triangle ; equilateral triangle ; 

isosceles triangle 58 

Scalene triangle ; a quadrangle ; quadrilateral or tetragon 5c 

Khomboid ; trajjczoid ; trapezium 6c 

The construction of polygons 61 

The names of regular polygons 62 

The angles of regular polygons ; the ellipse 63 

Form of a true ellipse 69 

'I'hc use of a tranunel for drawing an ellipse 72 

Tn <lr;\w a parabola mechanically 73 

Tf' draw a parabola by lines 74 

To <lraw a heart cam 75 



4 



CONTENTS. vii 

CHAPTER IV. 
SHADOW LINES AND LINE-SHADING. 

Section lining or cross-hatching 77 

To represent cylindrical pieces one within the other ; to represent a number 

of pieces one within the other . , 78 

To represent pieces put together and having slots or key ways through them. 79 

Effects of shading or cross-hatching 80 

Lines in sectional shading or cross-hatching made to denote the material of 

which the piece is composed — lead, wood, steel, brass, wrought iron, 

cast iron 81 

Line-shading 82 

The shade line to indicate the shape of piece ; representation of a washer. ... 83 
A key drawn with a shade line ; shade line applied to a nut ; a German 

pen regulated to draw lines of various breadths 84 

Example of line -shading in perspective drawing, shown in a pipe threading 

stock and die 85 

A cylindrical pin line-shaded ; two cylindrical pieces that join each other; a 

lathe centre ; a piece having a curved outline 86 

Line-shading applied to a Taall or sphere ; applied to a pin in a socket shown 

in section 87 

A piece of tube, where the thickness of the tube is shown ; where the 

hollow or hole is seen, the piece shown in section ; where the body is 

bell-mouthed and the hollow curve shown by shading 88 

Example of line-shading to denote the relative distances of various surfaces 

from the eye. 89 

Line-shading to denote that the piece represented is of wood ; shade-lines 

being regular or irregular 90 

CHAPTER V. 

MARKING DIMENSIONS. 
Examples in marking dimensions 9I 

CHAPTER VL 

THE ARRANGEMENT OF DIFFERENT VIEWS. 

The different views of a mechanical drawing ; elevation ; plan ; general 

view ; a figure to represent a solid cylinder 94 



yiji contents: 

To represent the different sides of a cube; the use of a cross to denote a 

square 95 

A triangular piece requires two or three views 96 

To represent a ring having hexagon cross section; exan\ples ; a rectangular 

piece in two views 98 

The position of the piece when in its place determines the name of the view 

in the drawing 103 

View of a lever 105 

Best method of projecting one view from another; the two systems of differ- 
ent views of a piece / 106 

CHAPTER VII. 

EXAMPLES IN BOLTS, NUTS AND POLYGONS. 

To represent the thread of a small screw II2 

A bolt with a hexagon head , . . . . 113 

United States standard sizes for forged or unfinished bolts and nuts 116 

The basis of the Franklin Institute or United- States standard for bolts and 

nuts ; hexagonal or hexagon heads of bolts 1 18 

Comparison of hexagon and square heads of bolts ; chamfers 1 20 

"Without chamfer; best plan for view of both square and hexagon heads ... 123 

Drawing different views of hexagon heads 125 

To draw a square-headed bolt; to draw the end view of a hexagon head. . 125 

Use of the triangle to divide circles 129 

Scales giving the length of the sides of polygons 135 

To find what a square body which measures one inch on each side meas- 
ures across the corners; to find what diameter a cylindrical piece of 
wnod must be turned to which is to be squared, and each side of which 

square must measure an inch 136 

To find a radius across corners of a hexagon or a six-sided figure, the length 

of a side being an inch 1 38 

To draw a stud 142 

To pencil in a cap nut ; pencilling for a link having the hubs on one side 

only 145 

Link with hubs on both sides ; juncil lines for a double eye or .1 kiuicldf: 

j'>inl 146 

Double eye or knuckle joint with an off^-t ; a connecting lod end 147 



CONTENTS, \^ 

A rod end with a round stem 148 

A bolt with a square under the head 149 

Example in which the corner where the round stem meets the square 
under the head is sharp; a centre punch giving an example in 
which the flat sides gradually run out upon a circle, the edges forming 
curves 150 

CHAPTER VIII. 

SCREW THREADS AND SPIRALS. 

Screw threads for small bolts with the angles of the thread drawn in, and 

the method of doing this 152 

A double thread ; a round top and bottom thread such as the Whitworth 

thread; a left hand thread; to draw screw threads of a large diameter. 156 

Drawing the curves for screw threads 157 

To draw the United States standard thread 160 

To draw a square thread 162 

Form of template for drawing the curves of threads 165 

To show the thread depth in a top or end view of a nut ; to draw a spiral 

spring 1 66 

To obtain an accurate division of the lines that divide the pitch 167 

CHAPTER IX. 

EXAMPLES FOR PRACTICE. 

A locomotive spring ; a stufiSng box and gland ; v.orking drawings of a 
coupling rod ; dimensions and directions marked ; a connecting rod 
drawn and put together as it would be for the lathe, vise, or erecting 

shop 169 

Drawings for the blacksmith 172 

A locomotive frame 1 74 

Reducing scales ^ . . 175 

Making a drawing to scale 177 

CHAPTER X. 
PROJECTIONS. 

A spiral wound around a cylinder whose end is cut off at an angle 178 



X CONTENTS. 

A cylindrical body joining another at a right-angle; a Tee for example.. .. i8o 

Other examples of Tees i8i 

Example of a cylinder intersecting a cone ig6 

A cylindrical body whose top face if viewed from one point would appear as 

a straight line, or from another a circle l88 

CHAPTER XI. 

DRAWING GEAR WHEELS. 

Names of the curves and lines of gear teeth 193 

How to draw spur wheel teeth 194 

Professor Willis' scale of tooth proportions 195 

The application of the scale 197 

How to find the curve for the tooth face 198 

To trace hypocycloides for the flanks of teeth 200 

Sectional view of a section of a wheel for showing the dimensions through 

the arms and hub . . . . , 202 

To draw an edge view of a wheel ; rules for drawing the teeth of wheels ; 

bevel gear wheels 203 

The construction 10 find the curves 204 

To draw the arcs for the teeth 205 

To draw the pitch circle of the inner and small end of the pinion teeth. . . . 206 

One-half of a bevel gear and an edge view projected from the same 207 

A pair of bevel wheels shown in section ; drawing of a part of an Ames 

lathe feed motion ; small bevel gears 208 

Example in which pait of the gear is shown with teeth in, and the remain- 
der illustrated by circles; drawings of part of the feed motion of a 

Nilcs horizontal tool work boring mill 209 

Three bevel gears, one of which is line-shaded; the construction of oval 
gearing; Professor Kankine's process for rectifying and subdiviiling cir- 
cular arcs 210 

V.Trious cxam])U's of laying out gear wheels .... 214 

CHAPTER Xn. 

PLOTTING MKGHANICAL MOTIONS. 
To fin<l how much motion an ccctnlric will give to its rod .... 223 



CONTENTS. Xi 

To find how much a given amount of motion of a long arm will move the 

short arm of a lever 224 

Example of the end of a lever acting directly on a shoe ; a short arm having 

a roller acting upon a larger roller 225 

A link introduced in the place of the roller to find the amount of motion of 
the rod ; a lever actuating a plunger in a vertical line, to find how much 
a given amount of motion of the long arm will actuate ihe plunger,. .. 226 
Two levers upon their axles or shafts, the arms connected by a link and one 

arm connected to a rod .' 227 

A lever arm and cam in one piece on a shaft, a shoe sliding on the line, 
and held against the cam face by the rod, to find the position of the 

face of the shoe agamst the cam 228 

To find the amount of motion imparted in a straight line to a rod, attached 

to an eccentric strap 229 

Examples in drawing the cut-off cams employed instead of eccentrics on 
river steamboats in the Western and Southern States. Different views 

of a pair of cams 232 

The object of using a cam instead of an eccentric 234 

Method of drawing or marking out a full stroke cam 237 

Illustration of the lines embracing cut-off cams of varying limits of cut-off... 240 
Part played by the stroke of the engine in determining the confoi-mation 
of cut-off cams ; manner of finding essential points of drawings of cut- 
off cams 241 

A cam designed to cut off the steam at five-eighths of the piston stroke. , . . 244 

Three-fourths and seven-eighths cams 246 

Necessary imperfections in the operations of cut-off cams 247 

Drawing representing the motion which a crank imparts to a connecting rod, 249 

Plotting out the motion of a shaper link quick return 250 

Plotting out the Whitworth quick return motion employed in machines.. .. 253 
Finding the curves for moulding cutters 257 

CHAPTER XIII. 

EXAMPLES IN LINE-SHADING AND DRAWING FOR LINE- 
SHADED ENGRAVINGS. 
Arrangement of idle pulleys to guide bolts from one pulley to another ; rep- 
resentation of a cutting tool for a planing machine 264 

Drawings for photo-engraving 267 



^11 CONTENTS. 

Drawing for an engraver in wood; drawings for engravings by the wax pro- 
cess 268 

Engraving made by the wax process from a print from a wood engraving ; 

engravings of a boiler drilling machine 269 

CHAPTER XIV. 

SHADING AND COLORING DRAWINGS. 

Coloring the journals of shafts; simple shading; drawing cast-iron, 

wrought iron, steel and copper 277 

Points to be observed in coloring and shading; colored drawings to be glued 
around their edges to the drawing board ; to maintain an even shade 

of color ; mixing colors 278 

To graduate the depth of tint for a cylindrical surface 279 

The size and use of brushes; light in shading; example for shading a Medart 

pulley 280 

Brush shading 281 

To show by the shading that the surfaces are highly polished ; representa- 
tion of an oil cup; representation of an iron planing machine 282 

Example in shading of Blake's patent direct acting steam^pump , 2S4 

Example of shading an independent condenser 288 

CHAPTER XV. 

EXAMPLES OF ENGINE WORK. 

Drawings of an automatic high speed engine; side and end views .of the 

engine ; vertical section of the cylinder through the valve face 2S9 

Valve motion ; governor 292 

Pillow box, block crank-pin, wheel and main journal . J94 

Side and edge view of the connecting rod •. 295 

A two hundred horse power horizontal steam boiler for a stationary engine; 

cross sectional view of the boiler shell 296 

Side clevjilion, end view of the boiler, and setting 297 

Working drawings of a one hundred horse power engine ; \\\\\ and side 
view of the bed plnte, wilh tlic main bearing and guide bars; cross 
sections of the bed plate; side clivation of the cylinder, with eml view 
of ihc same 299 



COI^TEXTS. Xiii 

'Steam chest side and horizontal cross section of the cylinder; steam chest 
and the valves ; cam wrist plate and cut-off mechanism ; shaft for the 
cam plate ; cross head ; side view and section through the centre of 

the eccentric and strap 301 

Construction of the connecting rod 303 

Index 305 



Mechanical Drawing 



SEIjIP-TJ^TJa-XIT. 



CHAPTER I. 

THE DRAWING BOARD. 

A Drawing Board should be of soft pine and free 
from knots, so that it will easily receive the pins'or tacks 
used to fasten down the paper. Its surface should be 
flat and level, or a little rounding, so that the paper 
shall lie close to its surface, which is one of the first 




requisites in making a good drawing. Its edges 
should be straiQ:ht and at a ricrht ancrle one to the 
Other, and the ends of the battens B B in Figure i 

2 (17) 



jg MECHANICAL DRAWING SELF-TAUGHT. 

should fall a little short of the edge A of the board, so 
that if the latter shrinks they will not protrude. The 
size of the board of course depends upon the size of 
the paper, hence it is best to obtain a board as small 
as will answer for the size of paper it is intended to 
use. The student will find It most convenient as well 
as cheapest to learn on small drawings rather than 
large ones, since they take less time to make, and cost 
less for paper; and although they require more skill to 
make, yet are preferable for the beginner, because 
he does not require to reach so far over the board, and 
furthermore, they teach him more quickly and effec- 
tively. He who can make a fair drawing having 
short lines and small curves can make a better one 
if it has large curves, etc., because it is easier to draw^ 
a large than a very small circle or curve. It is un- 
necessary to enter into a description of. the various 
kinds of drawing boards In use, because If the student 
purchases one he will be duly informed of the kinds 
and their special features, while if he Intends to make 
one the sketch in Fiorure i will olve him all the infor- 
matlon he requires, save that, as before noted, the 
wood must be soft pine, well seasoned and free from 
knots, while the battens B should be dovetailed in and 
the face of the board trued after they are glued and 
driven in. To true the edges square, it Is best to 
make the two longest edges parallel and straight, and 
then the ends may be scjuared from those long edges. 

TIIK T SQUARE. 

Drawing scjuares or T squares, as they are termed, 
are made of wood, of hard rubber and of steel. 



THE DRAWING BOARD. 



19 



There are several kinds of T squares ; in one the 
blade is solid, as it is shown in Figure 5 on page 20 ; in 
another the back of the square is pivoted, so that the 
blade can be set to draw lines at an anele as well as 
across the board, which is often very convenient, 
although this double back prevents the triangles, when 
used in some positions, from coming close enough to 
the left hand side of the board. In an improved 
form of steel square, with pivoted blade, shown in 
Figure 2, the back is provided with a half circle divided 




Fig. 2. 

into the degrees of a circle, so that the blade can be 
set to any required degree of angle at once. 





THE TRIANGLES. 

Two triangles are all that are absolutely necessary 
lor a beginner. The first is that shown in Figure 3, 



20 



MECHANICAL DRAWING SELF-TAUGHT. 



which Is called a triangle of 45 degrees, because Its 
edge A is at that angle to edges B and C. That in 
Figure 4 is called a triangle of 60 degrees, its edge A 
being at 60 degrees to B, and at 30 degrees to C. The 
edges P and C are at a right angle or an angle of 90 
degrees in both figures ; hence they are in this respect 
alike. By means of these triangles alone, a great 
many straight line drawings may be made with ease 
without the use of a drawing square ; but it is better 
for the beginner to use the square at first. The man- 
ner of using these triangles with the square Is shown 




Fig. 5- 

in Figure 5, in which the triangle, Figure 3, is shown in 
three positions marked D E F, and that shown in Fig- 
ure 4 is shown in three positions, marked respectively 
Ct H and I. It is obvious, however, that by turnlng 
I over, end for end, anodier position is attained. The 
usefulness in these particular triangles is because in 
tlie various positions shown they are capable of use; 
for drawing a very large proportion of the lines that 
occur in mechanical drawing. The; principal recpiire- 
m(!nt in their use is to hold them firmly to tlu^ square- 



THE DRAWING BOARD. 



21 



blade without moving it, and without permitting them 
to move upon it. The learner will find that this is 
best attained by so regulating the height of the 
square-blade that the line to be drawn does. not come 
down too near the bottom of the triangle or ed^e of 
the square-blade, nor too high on the triangle ; that is 
to say, too near its uppermost point. It is the left- 
hand edge of the triangle that is used, whenever it can 
be done, to produce the required line. 




Fiof. 6. 



CURVES. , 

To draw curves that are not formed of arcs or parts 
of circles, templates called curves are provided, exam- 
ples of these forms being given in Figure 6. They 
are made in wood and in hard rubber, the latter being 
most durable ; their uses are so obvious as to require 
no explanation. It may be remarked, however, that 
the use of curves gives excellent practice, because 
they must be adjusted very accurately to produce 
good results, and the drawing pen must be held in the 



2-2 



ME CHA NIC A L DRA V\ y.\ 'G SEL F- TA UGHT. 



same vertical plane, or the curve drawn will not be 
true In Its outline. 

DRAWING INSTRUMENTS. 

It Is not Intended or necessary to enter Into an 
elaborate discussion of the various kinds of drawing 
instruments, since the purchaser can obtain a good 
set of drawing instruments from a reputable dealer by- 
paying a proportionate price, and TcmsX per force learn 
to use such as his means enable him to purchase. 
It is recommended that the beginner purchase as 
good a set of instruments as his means will permit, 
and that if his means are limited he purchase less 
than a full set of Instruments, having the same of good 
quality. 

All the instruments that need be used in the exam- 
ples of this book are as follows : 

A small spring bow-pen for circles, a lining pen or 
pen for straight lines, a small spring bow-pencil for 
circles, a large bow-pen with a removable leg to re- 
place by a divider leg or a pencil leg, and having an 
extension piece to increase its capacity. 

The spring bow-pen should have a stiff spring, and 
should be opened out to Its full capacity to see that 
the spring acts well when so opened out, keeping the 
legs stiff when opened for the larger diameters. The 
purchaser should see that the joint for opening and 
closing the legs is an easy ])ut not a loose fit on the 
screw, and that the legs will not move sideways. To 
test this latter, which is of great importance in the 
spring bow-pencil as well as in die pen, it is well to 
close the legs nearly together and taking one leg \\\ 



I 



THE DRAWING BOARD. 23 

one hand and die odier leg in the odier hand (between 
the forefinger and thumb), pushing and pulling them 
sideways, any motion in that direction being sufficient 
to condemn the instrument. It is safest and best to 
have the two legs of the bow-pen and pencil made 
from one piece of metal, and not of two separate 
pieces screwed together at the top, as the screw will 
rarely hold them firmly together. The points should 
be long and fine, and as round as possible. In very 
small instruments separate points that are fastened 
with a screw are objectionable, because, in very small 
circles, they hide the point and make it difficult to ap- 
ply the instrument to the exact proper point or spot 
on the drawinor. 

The joints of the large bow or circle-pen should 
also be somewhat stiff, and quite free from side motion, 
and the extension piece should be rigidly secured 
when held by the screw. It is a good plan in purchas- 
ing to put in the extension piece, open the joint 
and the pen to their fullest, and draw a circle, moving 
the pen in one direction, and then redraw it, moving it 
in the other direction, and if one line only appears and 
Lxiat not thickened by the second drawing, the pen is a 
good one. 

The lead pencil should be of hard lead, and It Is 
recommended that they be of the H, H, H, H, H, H, 
in the English grades, which corresponds to the V, V, 
H, of the Dixon grade. The pencil lines should be 
made as lightly as possible; first, because the presence 
of the lead on ' the paper tends to prevent the ink 
from passing to the paper; and, secondly, because in 
rubbing out the pencil lines the ink lines are re- 



24 



MECHANICAL DRAWING SELF-TAUGHT. 




Fig. 8. 



duced In blackness and the surface of the paper be- 
comes roughened, so that it will soil easier and be 
harder to clean. \w order to produce fine pencil lines 
without requiring a very frequent 
sharpening of the pencil it is best 
to sharpen the pencil as in Figures 
7 and 8, so that the edge shall be 
long in the direction in which it is 
moved, which is denoted by the 
arrow in Figure 7. But when very 
fine work is to be done, as in the 
case of Patent Office drawings, a 
long, round point is preferable, be- 
cause the eye can see plainer just 
where the pencil will begin to 
mark and leave off; hence the pencil lines will not be 
so liable to overrun. 

In place of the ordinary wood-covered lead pencils 
there may be obtained at the drawing material stores 
pencil holders for holding the fine, round sticks of 
lead, and these are by far the best for a learner. They 
are easier to sharpen, and will slip in the holder, giving 
warning when the draftsman is pressing them too hard 
on the paper, as he is apt to do. The best method of 
trimming these leads, as also lead pencils after they 
have been roughly shaped, is with a small fine file, 
holding the file still and moving the pencil; or a good 
piece of emery paper or sand paper is good, moving 
the pencil as before. 

All lines in pencilling as in Inking in should bt^gin at 
th(; l(ift hand and be drawn towards die right, or when 
triangles are used the lines are begun at the boUom 



THE DRAWING BOARD. 2$ 

and dravyn towards die top or away from the operator. 
The rubber used should not be of a harsh grade, since 
that will roughen the face of 'the paper and probably 
cause the ink to run. The less rubbing out the bet- 
ter the learner will progress, and the more satisfaction 
he will receive from the results. If it becomes neces- 
sary to scratch out it is best done with a penknife 
well sharpened, and not applied too forcibly to the 
paper but somewhat lightly, and moved in different 
and not all in one direction. After the penknife the 
rubber may sometimes be used to advantage, since it 
will, if of a smooth grade, leave the paper smoother 
than the knife. Finally, before inking in, the surface 
that has been scraped should be condensed again by 
rubbing some clean, hard substance over it which will 
prevent the ink from spreading. The end of a paper- 
cutter or the end of a rounded ivory handled drawing- 
instrument is excellent for this purpose. 






Fig. 9. Fig. 10. 

It is well to use the rubber for general purposes in 
such a way as to fit It for special purposes ; thus, 
in cleaning the sheet of paper, the rubber may be 
applied first, as in Figure 9, as at A, and then as at B, 
and if it be moved sideways at the same time it will 
wear to the form shown in Figure 10, which will enable 
it to be applied along a line that may require to be 
rubbed out without removing other and neighboring 



26 MECHANICAL DRAWING SELF-TAUGHT. 

lines. If the rubber is in the form of a square stick 
one end may be bevelled, as in Figure ii, which is an 





Fig. II. Fig. 12. 

excellent form, or it may be made to have a point, as 
in Figure i 2. The object is in each case to enable 
the rubber action to be confined to the desired loca- 
tion on the paper, so as to destroy its smooth surface 
as little as possible. 

For simple cleaning purposes, or to efface the pen- 
cil lines when they are drawn very lightly, squares of 
sponge-rubber answer admirably, these being fur- 
nished by the dealers in drawing materials. 

A piece of bread will answer a similar purpose, but 
it is less convenient. 

P'or glazed surface paper, as Bristol-board, the 
smoothest rubber must be used, the grade termed 
velvet rubber answering well. 

THK DRAWINC; I'Al'KR. 

Whatever kind of drawing paper be used it should 
be kept dry, or the ink, however good it may be. will 
be apt to run and make a tliick h'ne that will not have 
the sharp, clean edges necessar\ to make liii(>s look 
well. 

Drawing paper is made in various qualities, kinds^ 



THE DRAIVIXG BOARD. 



27 



and forms, as follows : The sizes and names of paper 
made in sheets are : 



Cap, 


13X 


16 inches. 


Demy, - 


20 X 


15 ' 




Medium, 


22 X 


17 ' 




Royal, - 


24 X 


19 ' 




Super Royal, - 


27 X 


19 ' 




Imperial, 


30 X 


21 




Elephant, 


28 X 


22 




Columbier, 


34 X 


23 < 




Atlas, - 


Zl, X 


26 ' 




Theorem, 


34 X 


28 ' 




Double Elephant, - 


40 X 


26 ' 




Antiquarian, - 


52 X 


31 ' 




Emperor, 


40 X 


60 ' 




Uncle Sam, - 


48 X 120 





the thickness of the sheets increasing with their 
size. Some sheets of paper are hot pressed, to give a 
smoother surface, and thus enable cleaner-edged iine.-^ 
to be drawn. 

For large drawings paper is made in rolls of various 
widths, but as rolled paper is troublesome to lay fiat 
upon the drawing board, it is recommended to the 
learner to obtain the sheets, which may be laid sutli- 
ciently flat by means of broad headed pins, such as 
shown in Figure 13, which are called thumb ^~7,~^ 
tacks. These are forced through the paper ' 

into the board at each corner, as in Figure ^ig-^3- 
14 at/ On account of the large diameter of the 
stems of these thumb tacks, which unduly pierce and 
damage the board, and on account also of their heads, 
by reason of their thickness, coming in the way of the 



28 



MECHANICAL DRAWING SELF-TAUGHT. 



square blade, it will be found preferable to use the 
smallest sizes of ordinary iron tacks, with flat heads, 
whose stems are much finer and heads much thinner 




Fig. 14. 

than thumb tacks. The objection to ordinary tacks is 
that they are more difficult to remove, but they are, as 
stated, more desirable for use. 




Fig. 15- 
If the pap(!r is nearly the full size of the board, it 
docs not much matter as to its precise location on \\\v 
board, but otherwise it is best to place it as near the 
l(*ft-hand edcreof iIk bonrd as convenient, as is sliown 
in Fi<rur(* 14. 



THE DRAWING BOARD. 29 

The lower edge, D, Figure 1 5, of the paper, however, 
should not be placed too near the edge, A, of the 
board, because if the end P of the square back comes 
down below the edee of the board, it is more difficult 
to keep the square back true against the end of the 
board. 

The paper must lie flat upon and close to the sur- 
face of the board, and a sufficient number of tacks 
must be used to effect this purpose. 

Drawings that are to be intricate, or to contain a 
great many lines, as a drawing of an engine or of a ma- 
chine, are best pasted or glued all around the edges of 
the paper, which should first be dam.pened; but as the 
learner will scarcely require to make such drawings 
until he is somewhat familiar with and well practised 
in the use of the instruments, this part of the subject 
need not be treated here. 

TRACING PAPER. 

For taking tracings from drawings tracing paper or 
tracing cloth is used. They require to be stretched 
tightly and without wrinkles upon the drawing. To 
effect this object the mucilage should be thick, and 
the tracing paper should be darnpened with a sponge 
after it is pasted. It must be thoroughly dry before 
use, or the ink will run. 

Tracing cloth must be fastened by pins or thumb 
tacks, and not dampened. The drawing * should be 
made on the polished side of the cloth, and any color- 
ing to be done should be on the other side, and done 
after the tracing is removed from the drawing. 



30 MECHANICAL DRAWING SELF-TAUGHT, 



THE . INK. 

India Ink should always be used for mechanical 
drawing: First, because it lies upon and does not sink 
into the paper, and is, therefore, easily erased ; and, 
secondly, because it does not corrode or injure the 
drawing instruments. 

India ink Is prepared in two forms — in the stick and 
In a liquid form. The stick ink is mixed in what are 
termed* saucers, or cabinet saucers, one being placed 
above the other, so as to exclude the dust from set- 
tling in it, and also to prevent the rapid evaporation 
to which it is subject. 

The surface of the saucer should be smooth, as any 
roughness grinds the ink too coarsely, whereas the 
finer it is ground or mixed the easier it will flow, the 
less liability to clog the instruments, and the smoother 
and more flat it will lie upon the paper. In mixing 
the ink only a small quantity of water should be used, 
the stick of ink being pressed lightly upon the saucer 
and moved quickly, the grinding being continued 
until the ink is mixed quite thickly. This will grind 
the ink fine as it is mixed, and more water may be 
added to thin it. It is best, however, to let the ink 
be somewhat thick for use, and to keep it covered 
wlien not in use ; and though water may be added if 
it gets too tliick, yet ink that has once dried should 
not be mixed up again, as it will not work so well 
after having once dried. 

(3f liquid inks the Higgins ink Is by far the best, 
being quite equal to and much more convenient for 
use than the best stick ink. 



THE DRAWING BOARD. 



-w 



The difference between a good and an Inferior India 
ink lies chiefly in the extent to which the lamp-black, 
which is the coloring matter, form's with the water a 
chemical solution rather than a mechanical mixture. 
In inferior ink the lamp-black is more or less held in 
suspension, and by prolonged exposure to the air will 
separate, so that on being spread the solid particles 
will aggregate by themselves and the water by itself 

This explains why draughtsmen will, after the ink 
has been exposed to the air for an hour or two, add a 
drop 6f mucilage to it; the mucilage thickening the 
solution, adding weight to the water, and deferring 
the separadon of the lamp-black. 

A good India ink is jet black, flows easily, lies close 
to, does not stand upon or sink into the paper, and 
has an even lustre, the latter being an indication of 
fineness. The more perfect the incorporation of the 
lamp-black with the water the easier the ink will flow, 
the less liable it is to clog the instruments, the more 
even and sharp the edges of the lines, and the finer 
the lines that may be drawn. 

Usually India ink can only be tested by actual trial; 
but since it is desirable to test before purchasing it, it 
may be mentioned that one method is to mix a litde 
on the finger nail, and if it has a " bronzy " gloss it is 
a good indication. It should also spread out and dry 
without any tendency to separate. 

The best method of testing is to mix a very litde, 
and drop a single drop in a tumbler of clear water. 
The best ink wall diffuse itself over the surface, and if 
the water is disturbed will diffuse itself through the 
water, leaving it translucent and black, with a slight 



22 MECHANICAL DRAWING SELF-TAUGHT. 

tinofe of bronze color. A coarser Ink will act in a 
similar manner, but make the water somewhat opaque, 
with a blue-black, or dull, ashy color. A still coarser 
ink will, when diffused over the surface of the water, 
show fine specks, like black dust, on the surface. This 
is readily apparent, showing that the mixture of the 
ink Is not homog^eneous. 

When it Is an object to have the lines of a drawing 
show as black as possible, as for drawings that are to 
be photo-engraved, the Ink should be mixed so thickly 
as to have a tendency to lift when a body, such as a 
lead pencil, is lifted out of It. For Patent Office drawr 
Ings some will mix it so thickly that under the above 
test it appears a little stringy. 

The thicker the ink can be used the better, because 
the tendency of the carbon to separate is less ; and it 
is for this reason that the test mentioned with a tum- 
bler of water is so accurate. When Ink Is to be used 
on parchment, or glossy tracing-paper, it will flow 
perfectly if a few drops of ox-gall be mixed with It ; 
but on soft paper, or on bristol board, this will cause 
the ink to spread. 

For purposes of measurement, there are special 
rules or scales of steel and of paper manufactured. 
The steel rules are finely and accurately divided, and 
some are of triangular form, so that when laid upon 
the paper the lines divided will He close to the paper, 
and the: light will fall direcdy on the ruled surface. 
Trianguhir rules or scales are therefore much superior 
to flat ones. The object of having a paper rule or 
scale Is, that the paper will expand and contract under 
varying degrees of atmospheric moisture, the same as 
the drawing paper docs. 



THE DRAWIXG BOARD. 



33 



Figure 1 6 represents a triangular scale, having upon 
It six different divisions of the inch. These are made 



I M M I I i I 1 1\ llllliil MM 

94 92 90 88 86 \ \9 8 7 6 5 4 3 2 I '^ 



^ 



\^>\>>\»N 



^ 



Fig. i6. 

In different patterns, having either decimal divisions 
or the vulgar fractions. Being made of steel, and 
nickel-plated, they are proof against the moisture of 
the fingers, and are not subject to the variation of 
the wooden scale. 



\ 





CHAPTER II. 

THE PREPARATION AND USE OF THE INSTRUMENTS. 

The points of drawing Instruments require to be 
very accurately prepared and shaped, to enable them 
to make clean, clear lines. The object is to have the 
points as sharp as they can be made without cutting- 
the paper, and the curves as even and regular as pos- 
sible. 

The lining pen should be formed as In Flgun? 17, 
which presents an edge and a front 
view of the points. The Inside 
faces should be flat across, and 
slightly curved In their lengths, as 
Fig. 17. Fig. 18. shown. If this curve is too great, 
as shown exaggerated in Figure 18, the body of the 
ink lies too near the point and Is apt to flow too freely, 
running over the pen-point and making a thick, ragged 
line. On the other hand, if the inside faces, between 
which the Ink lies, are too parallel and narrow near 
the points, die Ink dries In the pen, and renders a too 
frequent cleaning necessary. Looking at the face of 
ihr. pen as at A in I^gure 17, its point should have an 
even curve, as sliown, the edge being as sharp as it 
can be made witliout cutting the drawing paper. 
Upon this quality deixmds tlie fineness and cleanness 
of the lines it will make. This thin edge should ex- 
(M) 



PREPARAriOX AND USE OF INSTRUMENTS. 35 

tend around the curve as far as the dotted hne, so 
that it will be practicable to slant the pen in either of 
the directions shown in Figure 19; and it is obvious 



Fig. 19. Fig. 20. 

that its thickness must be equal around the arc, so 
that the same thickness of line will be drawn whether 
the pen be held vertical or slanted in either direction. 

The outside faces of the pen should be slightly- 
curved, so that when held vertically, as in Figure 20 
(the dotted line representing the centre of the length 
of the instrument), and against the square blade S, 
the point will meet the paper a short distance from 
the lower edge of S as shown. By this means it is 
not necessary to adjust the square edge exactly coin- 
cident with the line, but a little way from it. This is an 
advantage for two reasons : first, the trouble* of set- 
ting the square-edge exactly coincident is avoided, and, 
secondly, the liability of the ink to adhere to the ^A<g^ 
of the square-blade and flow on to the paper and 
make a thick, ragged line, is prevented. 

The square being set as near to the line as desired, 
the handle may be held at such an angle that the pen- 
point will just meet the line when sloped either as in 
Figure 21 or 22. If, however, the slope be too much 
in the direction shown in Figure 21, practice is neces- 
sary to enable the drawing of straight lines if they be 
long ones, because any variation in the angle of the 



^6 MECHANICAL DRAWING SELF-TAUGHT. 

instrument to the paper obviously vitiates the straight- 
ness of the Hne. If, on the other hand, the square be 
too close to the line, and the pen therefore requires 




Fig. 21. Fig. 22. 

to be sloped as in Figure 22, the ink flowing from the 
pen-point is apt to adhere to the square-edge, and the 
result will be a ragged, thick line, as shown in Fig- 
ure 23. 

f 




Fig. 23. Fig. 24. Fig. 25. Fig. 26. 

Each of the legs should be of equal thickness at 
the pen-point edge, so that when closed together the 
point will be in the middle of the edge. The widdi 
and curve of each individual point should be quite 
equal, and the easiest method of attaining this end is 
as follows : 

Take a small slip of Arkansas oil-stone, and with 
the pen-points closed firmly by the screw trim the pen- 
edges to the required curve as shown at A, Figure 17, 
making the curve as even as possible. Then stone 
the faces until tliis curve is brought u|) to a sharp 
edge at the point between the two« pen-legs forming 
the point. 



PREPARATION AND USE OF INSTRUMENTS. 37 

Next take a piece of ooo French emery paper, lay 
it upon some flat body like the blade of a square, and 
smooth the curve of the edge enough to take off the 
fine, sharp edge left by the oil-stone; then apply the 
outside flat faces of the pen to the emery paper again, 
bringing the pen-edge up sharp. 

The emery paper will simply have smoothed and 
polished the surfaces, still leaving them too sharp, so 
sharp as to cut the paper; and to take ofl" dils sharp 
edge (which must first be done on die inside faces) 
open the pen-points as wide as the screw will permit. 
Then wrap one thickness of the emery paper upon a 
thin blade, as upon a drawing-triangle, and pass the 
open pen-points over It, and move the instrument end- 
wise, taking care to keep the inside face level with the 
surface of the emery paper, so that the pen-points shall 
not cut through. Next close the pen-points with the 
screw until they nearly, but not quite, touch, and sweep 
the edge of the pen-point along the emery paper under 
a slight pressure, so moving the handle that at each 

stroke the whole lenorth around the curved end of the 
<_> 

pen will meet the emery surface. During this motion 
the Inside faces of the pen-point must be held as nearly 
vertical as possible, so as to keep the two halves of the 
pen-point equal. 

The pen Is now ready for use, and will draw a fine 
and clean line. 

It is not usual to employ emery paper for the pur- 
pose indicated, but it w^ill be found very desirable, 
since it leaves a smoother surface and edgfe than the 
oil-stone alone. 

Circle-pens are more difficult to put in order than 



^3 mechaaucal drawing self-taught. 

the straight-line pen, especially those for drawing the 
smallest circles, which cannot be well drawn unless the 
pen Is of the precise right shape and in the best con- 
dition. 

A circle-pen Is shown In Figure 24, in which A rep- 
resents the point-leg and B the pen-leg. The point- 
leg must be the longest because It requires to enter 
the drawing paper before the pen meets the surface. 
The point should be sharp and round, for any edges 
or angles on It will cause It to widen the hole In the 
paper when it is rotated. To shape the points to pre- 
vent the enlargement of the centre in the paper is one 
of the most Important considerations in the use of this 
instrument, especially when several circles require to 
be drawn from the same centre. To accomplish this 
end the Inside of the point-leg should be, as near as 
possible, parallel to the length of the Instrument (which 
Is denoted In Figure 24 by the dotted line) when the 
legs are closed, as in the figure. If the point Is at 
an angle, as shown In Figure 25, It Is obvious that 
rotating It will enlarge the top of the centre in die 
drawing paper. The point should be sharp and smooth 
on its circumferential surface, and so much longer than 
the pen-point that It will have sufficient hold In the 
j)aper when the Instrument stands vertical and the 
pen-point meets the surface of it, which amount Is 
about 64th of an Inch. 

We may now consider the shape of the pen-point. 
Its iiisitle surfaces should be flat across and to the curve 
shown in iMgure 24, not as shown exaggerated in Fig- 
ure 25, because in the latter the body of the ink will 
bj loo near the pen-poim, and but little can be placed 



PREPARATION AND USE OF INSTRUMENTS. ^q 

in it without causincr it sometimes to flow over the 
edges and down the outside of the pen. 

A form of pen-point recently introduced is shaped 
as in Figure 26, the object being to have a thin stream 
of ink near the marking pen-point and the main body 
of the ink near at hand, instead of extending up the 
pen, as would be the case w^ith Figure 24. The ad- 
vantacre thus gained is that the ink lies in a more 
solid body, and having less area of surface exposed to 
the air will not dry so quickly in the pen ; but this is 
more than offset by the liability of the ink to flow over 
the crook at A, and cause the pen to draw a thick 
ragged line. The pen-point must be slightly inclined 
toward the needle-point, to the end that they may ap- 
proach each other close enough for drawing very 
small circles, but it should also stand as nearly verti- 
cal as will permit that end to be attained. As this pen 
is for drawing small circles only, it does not require 
much ink, and hence may be somewhat close together, 
as in Figure 24 ; this has the advantage that the point 
is not hidden from observation. 

In forming the pen-point the greatest refinement is 
necessary to enable the drawing of very small true 
circles, say /5th of an inch, or less, in diameter. The 
requirements are that the pen-point shall meet the 
surface of the paper when* the needle-point has en- 
tered it sufficiently to give the necessary support, and 
that the instrument shall stand vertical, as shown by 
the dotted line in Figure 24. Also, that the pen shall 
then touch the paper at a point only, this point being 
the apex of a fine curve ; that this curve be equal on 
each side of the point of contact w^ith the paper; that 



^O MECHANICAL DRAWING SELF-TAUGHT. 

both halves forming the pen be of equal thickness 
and width at the pointed curve ; and that the point be 
as sharp as possible v^ithout cutting the paper. 

The best method of attaining these ends is as fol- 
lows : On each side of the pen make, with an oil-stone, 
a flat place, as C D, Figure 27 (where the pen-point 




c 
r 
Figures 27. 28. 29. 30. 31. 32. 

is shov/n magnified), thus bringing both halves to an 
edge of exactly equal length, and leaving the point 
flat at D. These flat places must be parallel to one 
another and to the joint between the two halves of the 
pen. As the oil-stone may leave a slightly ragged 
edge, it Is a good plan to take a piece of 00 French 
emery paper, lay It on a flat surface, and holding the 
instrument vertically remove the fine edge D until it 
will not cut. Then with the oil-stone shape the 
curved edcre as In Fieure 28, takincr care that the 
curve no more than brings the flat place D up to a 
true curve and leaves the edge sharp, with only the 
very point touching the paper, which is rej^resented in 
the cut by the horizontal line. 

The point must have a sharp edge all around the 
curve, and tlie two halves must be exacdy e(]ual in 
width, for if one half is wider tlian the other, as in 
Figure 29 at a, or as in Figure 30 at /;, it will be Im- 
possible to draw a vc^y small circle true. So, like- 
wise, the two halves of the pen must be of exacdy 



PREPARATION AND USE OF INSTRUMENTS. 41 

equal length, and not one half longer than the other, 
as In Figures 31 or 32, which would tend to cut the 
paper, and also render the drawing of true small cir- 
cles impracticable. 

When the pen is closed to draw a very small circle 
the two halves of the pen-leg should have an equal 
degree of contact with the surface of the paper, and 
then as the legs are opened out to draw larger circles 
the contact of the outside half of the pen will have 
less contact with the paper. The smaller the circle, 
the more difficult it is to keep the point-leg from slip- 
ping out of the centre, and the more difficult it is to 
draw a clear line and true circle ; hence the points 
should be shaped to the best advantage for drawing 
these small circles, by oil-stoning the pen, as already 
described, and then finishing it as follows : 

Afcer the oil-stoning, open the two valves of the 
pen-leg wide enough to admit a piece of 000 French 
emery paper wrapped once around a very thin blade, 
and move the pen endwise as described for the 
straight-line pen. This will smooth the inner surfaces 
and remove any fine wire-edge that the oil-stone may 
leave. Close the two halves of the pen again, and 
lightly emery-paper the outside faces, which will leave 
the edge sharp enough to cut the paper. The re- 
moval of the sharp edge still left, to the exact degree, 
requires great care. It may best be done by closing 
the pen until its two halves very nearly, but not quite, 
touch, then adjust it to mark a circle of about /g inch 
diameter, and strike a number of circles in different 
locations upon the surface of a piece of 0000 French 
emery paper. 



^2 MECHANICAL DRAWING SELF-TAUGHT. 

In marking these circles, however, let the instru- 
ment stand out of the perpendicular, and do very lit- 
tle while standing vertically. Indeed, it is well to strike 
.a number of half-circles, first from right to left and 
then from left to right, and finally draw a full circle, 
sloping the pen on one side, gradually raising it verti- 
cally, and finally sloping it to the other side. This will 
insure that the pen has contact at its extreme point, 
and leave that point fine and keen, but not enough so 
to cut the paper. To test the pen, draw small circles 
with the pen rotated first in one direction and then In 
the other, closing its points so as to mark a fine line, 
which, if the pen is properly shaped, will be clear and 
fine, while if improperly formed the circle drawn with 
the pen rotated in one direction will not coincide with 
that drawn while rotatingr it in the other. The same 
circle may be drawn over several times to make a 
thorough test. If a drawing instrument will draw a 
fine line correctly, it will be found to answer for thick 
lines which are more easily made. 

In thus preparing the instruments, the operator will 
find that if he occasionally holds the points in the 
right position with regard to the light, he will be able 
to see plainly if the work is proceeding evenly and 
(Hjually, for if one-half of the pen is thicker at tho 
point or edge than the other, it will show a brighter 
line. This is especially the case with instruments that 
have become dull by use, for in that .case the edges 
will be kn\\\<\ i\\\\w bright, and any inequality of thick- 
ness sliows plainly. 

It follow.s, from what has been said, that the needle- 
po'iU .'ind j)cn-p()inl 'Ji.-nl,] stand \-criieal whm in use, 



PREPARATION 4XD USE OF INSTRUMENTS. 



43 



and to effect this the Instruments, except in the 
smallest sizes, are provided with joints, such as shown 
at A and B in the bow-pencil or circle-pencil, in Fig- 
ure 2iZ' These joints should be sufficiently stiff that 





they will not move too easih; and yet will move rather 
than that the legs should sensibly spring without 
moving at the joint. The needle-point leg should be 
adjusted by means of the joint, to stand vertical, 
and the same remarks apply equally to the pen- 
leg ; but in the case of the pencil-leg it Is the pen- 
cil itself and not the leg that requires attention, 
the joint B being so adjusted that the pencil either 
stands vertical, or, what Is perhaps preferable, so that 



44 



MECHANICAL DRAWING SELF-TAUGHT. 



it stands inclined slightly towards the needle-point. 
In sharpening the pencil the inner face C may be made 
concave or at least vertical and flat, and the outer con- 
vex or else bevelled and flat, producing a fine and long 
edge rounded in its length of edge. In using the circle- 
pencil and circle-pen it will be found more convenient 
to rotate it in the direction of the arrow in Figure 34. 
It should be held lightly to the paper, and the learner will 
find that he has a natural tendency to hold it too firmly 
and press it too heavily, which is especially to be avoided. 
If in drawing a small circle the needle-point slips 
out of the paper, it is because the pencil-point is too 
long ; or, what is the same thing, the needle-point does 
not protrude far enough out from the leg. Or if the 
instrument requires to be leaned over too much to 
make the pencil or pen mark, it is because the pen or 
pencil is not far enough out, and this again may cause 
the needle-point to slip out of the paper. 




In V 



Mgurc 35 IS 



^'\". 35- 
lown a German instrumrm i-s 



pec- 



PREPARATION AND USE OF INSTRUMENTS. 



45 



ially designed to avoid this slipping. The peculiarity 
of this Instrument consists In the arrangement of the 
centre point, which remains stationary whilst the pen 




Fig. 36. 

or pencil, resting by its own weight on the paper, Is 
guided round by gently turning, without pressure, 
the small knob at the upper end of the tube. By this 



.5 MECHANICAL DRAWING SELF-TAUGHT. 

means the misplacing or sliding- of the centre-poinf 
and the cutting of the paper by the pen are avoided. 
By means of this fixed centre-point any number of 
concentric circles may be drawn, without making a 
hole of very distinguishable size on the paper. 




'* ffp-^'""^"^ 



Fig. 37- 
In applying the Ink to the bow-pen as to all other 
instruments, care must be taken that the ink lies be- 
tween the points only and not on the outside, for in 
the latter case the ink will flow down too freely and 
make a broad, ragged line, perhaps getting on the 
edge: of the sciuare blade or trianule, and causing a 
blol t)f ink oil the (h-awimr. 



PREPARATION AND USE OF INSTRUMENTS. ^y 

In using a straight line or lining pen with a T 
square it may be used as in Figure 36, being nearly 
vertical, as shown, and moved from left to right as de- 
noted by the arrow, S representing the square blade. 
But in using it, or a pencil, with a straight edge or a 
triangle unsupported by the square blade, the latter 
should be steadied by letting the fingers rest upon it 
while using the instrument, the operation being shown 
in Figure 2,7- The position, Figure 36, is suitable for 
long lines, and that in Figure 2,7 for small drawings, 
where the pen requires close adjustment to the lines. 



CHAPTER III. 



LINES AND CURVES, 



Although the beginner will find that a study of 
geometry is not essential to the production of such 
elementary examples of mechanical drawing as are 
given in this book, yet as more difficult examples are 
essayed he will find such a study to be of great ad- 
vantage and assistance. Meantime the followine ex- 
planation of simple geometrical terms is all that is 
necessary to an understanding of the examples given. 

The shortest distance between two points is termed 
the radius; and, in the case of a circle, means the dis- 
tance from the centre to the perimeter measured In a 
straight line. 

Dotted lines, thus, < >, mean the direction and 




I'-'g. 38. 



Fig. 39- 



Fig. 40. 



the points at which a dimension is taken or marked. 

Dotted lines, thus, , simply connect the same 

j)arts or lines in different views of the object. Thus in 
(48) 



LINES AND CURVES. 



49 



Figure 38 are a side and an end view of a rivet, and the 
dotted lines show that the circles on the end view 
correspond to the circle of the diameters of the head 
and of the stem, and therefore represent their diame- 
ters while showing that both are round. A straicrht 
line is in oreometrv termed a riorht line. 

A line at a right angle to another is said to be per- 
pendicular to it; thus, in Figures 39, 40, and 41, lines 
A are in each case perpendicular to line B, or line B 
is in each case perpendicular to line A. 

A point is a position or location supposed to have 




Fig. 41. Fig. 42. Fig. 43. 

no size, and In cases w^here necessary is Indicated by 
a dot. 

Parallel lines are those equidistant one from the 
other throughout their length, as in Figure 42. Lines 



\i 



Fig. 44. 



Fig- 45- 



Fig. 46. 



maybe parallel though not straight; thus, in Figure 43 
the lines are parallel. 



so 



MECHANICAL DRAWING SELF-TAUGHT. 



A line Is said to be prodiiced when it Is extended 
beyond its natural limits: thus, in Figure 44, lines A 
and B are produced in the point C. 

A line is bisected when the centre of its lenofth is 
marked: thus, line A in Figure 45 is bisected, at or in, 
as it is termed, e. 

The line boundlno- a circle is termed its circumfer- 
ence or periphery and sometimes the perimeter. 

A part of this circumference Is termed an arc of a 
circle or an arc; thus Figure 46 represents an arc. 




Fig. 47. Fig. 48. Fig. 49. 

When this arc has breadth it is termed a segment; 
thus Figures 47 and 48 are segments of a circle. A 
straight line cutting off an arc is termed the chord of 





l^^'K- 50- Fig. 51. 

the arc; thus, in Mgurc 48, line A Is the cliord of the 



arc. 



A quadrant of a circle is one quarter of ilic s:<nu' 



LINES AND CURVES. 



51 



being bounded on two of its sides by two radial lines, 
as in Figure 49. 

When the area of a circle that is enclosed within 
two radial lines is either less or more than one quar- 
ter of the whole area of the circle the ficrure is termed 
a sector; thus, in Figure 50, A and B are both sectors 
of a circle. 

A straight line touching the perimeter of a circle is 
said to be tangent to that circle, and the point at 
which it touches is that to which it is tangent; thus, in 
Figure 51, line A is tangent to the circle at point B. 
The half of a circle is termed a semicircle; thus, in 
Figure 52, A B and C are each a semicircle. 





Fig. 52- 



Fig. 53- 



The point from which a circle or arc of a circle Is 
drawn is termed Its centre. The line representing the 
centre of a cylinder is termed Its axis ; thus, in Figure 
53, dot </ represents the centre of the circle, and line 
b b the axial line of the cylinder. 

To draw a circle that shall pass through any three 
given points : Let A B and C In Figure 54 be the 
points through which the circumference of a circle is 
to pass. Draw line D connecting A to C, and line E 
connectlnor B to C. Bisect D in F and E in G. From 
F as a centre draw the semicircle O, and from G as 
a centre draw the semicircle P ; these two semicircles 
meeting the two ends of the respective lines D E. 



52 



MECHANICAL DRAWING SELF-TAUGHT. 



From B as a centre draw arc H, and from C the arc 
I, bisecting P in J. From A as a centre draw arc K, 
and from C the arc L, bisecting the semicircle O in 





Fig. 55- 
M, Draw a line passing through M and F, and a line 
passing through J and O, and where these two lines 
intersect, as at O, Is the centre of a circle R that will 
pass through all three of the points A B and C. 

To find the centre from which an arc of a circle 
has been struck : Let A A In Figure 55 be the arc 
whose centre is to be found. From the extreme ends 
of the arc bisect it In B. From end A draw the arc 
C, and from B the arc D. Then from the end A 
draw arc G, and from B the arc F. Draw line H 
passing through the two points of intersections of 
arcs C D, and line I passing through the two points 
of intersection of F G, and where H and I meet, as 
at J, is the centre from which the arc was drawn. 

yV degree of a circle is the 3J,, part of its circum- 
ference. The whol(! circumference is supposed to be 
divided into 360 equal divisions, which are called the 



LIXES AND CURVES. 



53 



degrees of a circle ; but, as one-half of the circle is 
simply a repetition of the other half, it is not neces- 
sary for mechanical purposes to deal with more than 
one-half, as is done in Figure 56. As the whole 
circle contains 360 degrees, half of it will contain 
one-half of that number, or 180; a quarter will 
contain 90, and an eighth will contain 45 degrees. 
In the protractors (as the instruments having the 
degrees of a circle marked on them are termed) 
made for sale the edges of the half-circle are marked 

V 




off into deofrees and half-decrees ; but it is sufficient 
for the purpose of this explanation to divide off one 
quarter by lines i o degrees apart, and the other by lines 
5 degrees apart. The diameter of the circle obviously 
makes no difference in the number of degrees con- 
tained in any portion of it. Thus, in the quarter 
from o to 90, there are 90 degrees, as marked ; but 
suppose the diameter of the circle were that of inner 
circle d, and one-quarter of it would still contain 90 
degrees. 



54 



MECHANICAL DRAWING SELF-TAUGHT. 



So, likewise, the degrees of one line to another are 
not always taken from one point, as from the point o, 
but from any one line to another. Thus the line 
marked 120 is 60 degrees from line 180, or line 90 is 
60 degrees from line 150. Similarly in the other 
quarter of the circle 60 degrees are marked. This 
may be explained further by stating that the point 
o or zero may be situated at the point from which the 
degrees of angle are to be taken. Here it may be 
remarked that, to save writing the word" degrees," 
it is usual to place on the right and above the figures 
a small °, as is done in Figure 56, the 60° meaning 
sixty degrees, the °, of course, standing for degrees. 

Suppose, then, w^e are given two lines', as a and b in 
Figure 57, and are required to find their angle one to 




Fig. 57- 



the other. Then, if wc have a protractor, we may 
ai)ply it to the lines and see how many degrees of 
angle thc^y contain. This word "contain " means how 
many degrees of angle tlK!re are between tlie lines, 



LINES AND CURVES. jC 

which, in the absence of a protractor, we may find by 
prolonging the Hnes until they meet in a point as at c. 
From this point as a centre we draw a circle D, pass- 
ing through both lines a, b. All we now have to do is 
to find what part, or how much of the circumference, of 
the circle is enclosed within the two lines. In the ex- 
ample we find it is the one-twelfth part ; hence the 
lines are 30 degrees apart, for, as the whole circle 
contains 360, then one-twelfth must contain 30, be- 
cause 360-7-12=30. 

If we have three lines, as lines A B and C in 
Figure 58, we may find their angles one to the other 




by projecting or prolonging the lines until they meet 
as at points D, E, and F, and use these points as the cen- 
tres wherefrom to mark circles as G, H, and I. Then, 
from circle H, we may, by dividing it, obtain the angle 



c5 MECHANICAL DRAWING SELF-TAUGHT. 

of A to B or of B to A. By dividing circle I we may 
obtain the angle of A to C or of C to A, and by 
dividing circle G we may obtain the angle of B to C 
or of C to B. y 

It may happen, and, indeed, generally will do so, 
that the first attempt will not succeed, because the 
distance between the lines measured, or the arc of 
the circle, will not divide the circle without having the 
last division either too long or too short, in which 
case the circle may be divided as follows : The com- 
passes set to its radius, or half its diameter, will 
divide the circle into 6 equal divisions, and each of 
these divisions will contain 60 deorees of anole, be- 
cause 360 (the number of degrees in the whole 
circle) -t-6 (the number of divisions) =60, the number 
of degrees in each division. We may, therefore, 
subdivide as many of the divisions as are necessary 
for the two lines whose decrees of anele are to be 
found. Thus, in Figure 59, are two lines, C, D, and 




it is required to find their angle one to the other. 
The circle is divided into six divisions, marked re- 
spectively from 1 to 6, the division being made from 



LINES AND CURVES. 



57 



the Intersection of line C with the circle. As both lines 
fall within less than a division, we subdivide that 
division as by arcs a, b, which divide it into three 
equal divisions, of which the lines occupy one division. 
Hence, it is clear that they are at an angle of 20 
degrees, because twenty is one-third of sixty. When 
the number of degrees of angle between two lines 
is less than 90, the lines are said to form an acute 
angle one to the other, but when they are at more 
than 90 degrees of angle they are said to form an 
obtuse angle. Thus, in Figure 60, A and C are at 




an acute angle, while B and C are at an obtuse angle. 
F and G form an acute angle one to the other, as also 
do G and B, while H and A are at an obtuse angle. 
Between I and J there are 90 degrees of angle ; 
hence they form neither an acute nor an obtuse 
angle, but what is termed a right-angle, or an angle 
of 90 degrees. E and B are at an obtuse angle. 
Thus it will be perceived that it Is the amount of in- 
clination of one line to another that determines its 



rg MECHANICAL DRAWING SELF-TAUGHT. 

angle, Irrespective of the positions of the Hnes, with 
respect to the circle. 

TRIANGLES. 

A right-angled triangle Is one In which two of the 
sides are at a rieht an^le one to the other. Fissure 
6 1 represents a right-angled triangle, A and B forming 



Riglit angle 
Triangle 




Obtihsa angle 
Triangle 




Fig. 62. 

a right angle. The side opposite, as C, is called the 
hypothenuse. The other sides, A and B, are called 
respectively the base and the perpendicular. 

Isoceles Triangle 
Equilateral 

Triangle 





1^'ig. 63. 

An acute-angled triangle has all its angles acute, 
as in Figure 63. 

An obtuse-angled triangle has one obtuse angle, as 
A, r'igure 62. 



LINES AND CURVES. 



59 



When all the sides of a triangle are equal in 
length and the angles are all equal, as in Figure 
^2)^ it is termed an equilateral triangle, and either 
of its sides may be called the base. When two 
only of the sides and two only of the angles are 
equal, as in Figure 64, it is termed an isosceles triangle, 
and the side that is unequal, as A in the figure, is 
termed the base. 



Scalene 
Triangle 




Fig. 66. 

When all the sides and angles are unequal, as in 
Figure 65, it is termed a scalene triangle, and either 
of its sides may be called the base. 

The angle opposite the base of a triangle is called 
the vertex. 



Fig. 67. 



Hhomb 
Fig. 68. 



A figure that is bounded by four straight lines is 
termed a quadrangle, quadrilateral or tetragon. 
When opposite sides of the figure are parallel to each 



6o 



MECHANICAL DRAWING SELF-TAUGHT. 



Other it is termed a parallelogram, no matter what 
the angle of the adjoining lines in the figure may be. 
When all the angles are right angles, as in Figure 66, 
the figure is called a rectangle. If the sides of a 
rectangle are of equal length, as in Figure 6^, the 
figure is called a square. If two of the parallel sides 
of a rectangle are longer than, the other two sides, as 
in Figure 66, it is called an oblong. If the length 
of the sides of a parallelogram are all equal and 
the angles are not right angles, as in Figure 6%, it 
is called a rhomb, rhombus or diamond. If two 
of the parallel sides of a parallelogram are longer 
than the other two, and the angles are not right 




Fig. 69. 



Trapezoid 

Fig. 70. 




Trapezium 

Fig. 71. 



angles, as in Figure 69, it Is called a rhomboid. 
If two of the parallel sides of a quadrilateral arc of 
unequal lengths and the angles of the other two 
sides are not equal, as in Figure 70, It Is termed a 
trapezoid. 

If none of tlie sides of a quadrangle are parallel, 
as in Figure 71, it is termed a trapezium. 



LINES AND CURVES. 6l 

THE CONSTRUCTION OF POLYGONS. 

The term polygon is applied to figures having flat 
sides equidistant from a common centre. From this 
centre a circle may be struck that will touch all the 
corners of the sides of the polygon, or the point of 
each side that is central in the length of the side. In 
drawing a polygon, one of these circles is used upon 
which to divide the figure into the requisite number 
of divisions for the sides. When the dimension of 
the polygon across its corners is given, the circle 





Fig. 71 <?. Fig. 72. 

drawn to that dim.ension circumscribes the polygon, 
because the circle is without or outside of the polygon 
and touches it at its corners only. When the dimen- 
sion across the fiats of the polygon is given, or when 
th6 dimension given is that of a circle that can be 
inscribed or marked within the polygon, touching its 
sides but not passing through them, then the polygon 
circumscribes or envelops the circle, and the circle is 
inscribed or marked within the polygon. Thus, in 
Figure 71 a, the circle Is Inscribed within the polygon, 
while in Figure 72 the polygon is circumscribed by 
the circle; the first is therefore a circumscribed and 



62 



MECHANICAL DRAWING SELF-TAUGHT. 



the second an Inscribed polygon. A regular poly- 
gon is on^ the sides of which are all of an equal 



length. 



NAMES OF REGULAR POLYGONS. 



A figure of 3 sides is called a Trigon. 



polygon 



4 




a 


' Tetragon. 


5 




(( 


Pentagon. 


6 




a 


Hexagon. 


7 




(( 


Heptagon. 


8 




(( 


Octagon. 


9 




a 


Enneagon or Nonagon 



The angles of regular polygons are designated by 
their degrees of angle, "at the centre" and "at the 
circumference." By the angle at the centre is meant 
the angle of a side to a radial line ; thus in Figure y^ 





'b- 73- -t^ig- 74. 

is a hexagon, and at C Is a radial line; thus the angle 
of the side D to C is 60 degrees. Or If at the two 
ends of a side;, as A, two radial lines be drawn, as B, 
C, then the angh^s of these two lines, one to the other, 
will be the "angle at tlie centre." The angle at tli(^ 
cirmmference is the angle of one side to its next 
neighbor; thus the angle at the circumference in a 
hexagon is 120 degrees, as shown in the figure for 



LINES AND CURVES. 63 

the sides E, F. It is obvious that as all the sides are 
of equal length, they are all at the same angle both 
to the centre and to one another. In Figure 74 is a 
trio-on, the angles at its centre beinor 120, and the 
angle at the circumference being 60, as marked. 
The angles of regular polygons : 

Trigon, at the centre, 120°, at the circumference, 60°. 



Tetragon, 




90°, 




90°. 


Pentagon, 




72°, 




108°. 


Hexagon, 




60°, 




I20^ 


Octagon, 




45°, 




i35°- 


Enneagon, 




40°, 




140°. 


Decagon, 




36°, 




144°. 


Dodecagon, 




30°, 




" 150°. 






THE ELLIPSE. 





An ellipse is a figure bounded by a continuous 
curve, whose nature will be shown presently. 

The dimensions of an ellipse are taken at its ex- 
treme length and narrowest width, and they are des- 
ignated in three ways, as by the length and breadth, 
by the major and minor axis (the major axis meaning 
the length, and the minor the breadth of the figure)^ 
and the conjugate and transverse diameters, the trans- 
verse meaning the shortest, and the conjugate the 
longest diameter of the figure. 

In this book the terms major and minor axis will 
be used to designate the dimensions. 

The minor and major axes are at a right angle one 
to the other, and their point of intersection is termed 
the axis of the ellipse. 

In an ellipse there are two points situated upon the 



64 



MECHANICAL DRAWING SELF-TAUGHT. 



line representing the major axis, and which are termed 
the foci when both are spoken of, and a focus when 
one only is referred to, foci simply being the plural 
of focus. Thes-e foci are equidistant from the centre 
of the ellipse, which is formed as follows : Two pins 
are driven in on the major^axis to represent the foci A 
and B, Figure 75, and around these pins a loop of 




Fig. 75. 

fine twine is passed ; a pencil point, C, is then placed 
in the loop and pulled outwards, to take up the slack 
of the twine. The pencil is held vertical and moved 
around, tracing an ellipse as shown. 

Now it is obvious, from this method of construction, 
tliat there will be at every point in the pencil's path a 
l(MTgth of twine from the final point to each of the foci, 
and a length from one foci to the other, and the length 
of twine in the loop remaining constant, it is demon- 
strated that if in a true ellipse we take an)' number 
of points in its curve, and for each point add together 
its distance to each focus, and to this add the distance 
apart of the foci, the total sum obtained will he the 
same for each i)oint taken. 



LINES AND CURVES. 65 

In Figures ']6 and ']'] are a series of ellipses marked 
with pins and a piece of twine, as already described. 
The corresponding ellipses, as A in both figures, were 




Fig. 76. 



Fig. 77. 



marked with the same loop, the difference in the two 
forms being due to the difference in distance apart of 
the foci. Again, the same loop was used for ellipses 
B in both figures, as also for C and D. From these 
figures we perceive that — 

1st. With a given width or distance apart of foci, 
the laro^er the dimensions are the nearer the form of 
the figure will approach to that of a circle. 

2d, The nearer the foci are together in an ellipse, 
having any given dimensions, the nearer the form of 
the figure will approach that of a circle. 

3d. That the proportion of length to width in an 
ellipse is determined by the distance apart of the foci. 

4th. That the area enclosed within an ellipse of a 
given circumference is greater in proportion as the 
distance apart of the foci is diminished ; and, 
5 



66 



MFXHANICAL DRAWING SELF-TAUGHT. 



5th. That an ellipse may be given any required 
proportion of width to length by locating the foci at 
the requisite distance apart 

The form of a true ellipse may be very nearly ap- 
proached by means of the arcs of circles, If the centres 
from which those arcs are struck are located In the 
most desirable positions for the form of ellipse to be 
drawn. 

Thus in Figure "]% are three ellipses w^hose forms 




Fig. 78. 

were pencilled in by means of pins and a loop of twine, 
as already described, but which were inked in by find- 
ing four arcs of circles of a radius that would most 
closely approach the pencilled line; a b are the foci 
of all tlire(; ellipses A, B, and C; the centre for the 
end curves of a arc^ at c and it and those for Its side 
arcs are at c and /; For 1^) the qwA centres are at ;'• 
and //, and the si(l(> centres at / andy. For C the end 
c:entr(!s are at /', /. .md tli(^ <^^<^ .rntn/^ at ;;/ and ?/. 



LINES AND CURVES. 



67 



It will be noted that, first, all the centres for the end 
curves fall on the line of the length or major axis, 
while all those for the sides fall on the line of width 
or the minor axis; and, second, that as the dimensions 
of the ellipses increase, the centres for the arcs fall 
nearer to the axis of the ellipse. Now in proportion 
as a greater number of arcs of circles are employed 
to form the figure, the nearer It will approach the 
form of a true-ellipse ; but in practice it is not usual 
to employ more than eight, while it is obvious that 
not less than four can be used. When four are used 
they will always fall somewhere on the lines on the 
major and minor axis ; but if eight are used, two will 




Fig. 79. 

fall on the line of the major axis, two on the line of 
the minor axis, and the remaining four elsewhere. 

In Figure 79 Is a construction wherein four arcs are 
used. Draw the line a b, the major axis, and at a 



58 MECHANICAL DRAWING SELF-TAUGHT. 

rieht anole to it the line c d, the minor axis of the 
fieure. Now find the difference between the lenoth 
of half the two axes as shown below the figure, the 
length of line /"(from g X.o i) representing half the 
length of the figure (as from a \,o e), and the length 
or radius from g to h equalling that from ^ to d ; 
hence from h to i is the difference between half the 
major and half the minor axis. With the radius ijii), 
mark from ^ as a centre the 2iVcs j k, and join j k by 
line /. Take half the length of line / and from j as a 
centre mark a line on a to the arc 7n. Now the radius 
oi m from e will be the radius of all the centres from 
which to draw the figure ; hence we may draw in the 
circle 7n and draw line s, cutting the circle. Then draw 
line 0, passing through m, and giving the centre /. 
From /we draw the line ^.cutting the intersection of 
the circle with line a and oivino- the centre r. From 
r we draw line s, meeting the circle and the line c, d, 
giving us the centre /. From t we draw line 21, pass- 
ing through the centre ;;/. These four lines o, q, s, n 
are prolonged past the centres, because they define 
what part of the curve is to be drawn from each 
centre: thus from centre m the curve from r^ to w is 
drawn, from centre / the curve from hi to x is drawn, 
r^rom centre 7^ the curve from x tor is drawn, and 
from centre p the curve from-j)' to v is drawn. It is 
to be noted, however, that after the point ;;/ is found, 
the remaining lines may be drawn very quickl), be- 
cause the line o from ;;/ to p may be drawn widi tlie 
triangle of 45 degrees resting on tiie stjuare blade. 
Tlie triangle may be turned over, set to ()()iiu /and 
line ^ drawn, and by turning ih<- iriuuLjIc a-ain the 



LINES AND CURVES. 



69 



line s may be drawn from point r ; finally the triangle 
may be again turned over and line 7t drawn, which 
renders the drawing of the circle ;;/ unnecessary. 

To draw an elliptical figure whose proportion of 
width to breadth shall remain the same, whatever the 
length of the major axis may be : Take any square 
figure and bisect it by the line A in Figure 80. Draw, 




in each half 01 the square, the diagonals E F, G H. 
From P as a centre with the radius P R draw the 
arc S E R. With the same radius draw^ from O as 
a centre the arc T D V. With radius L C draw 
arc R C V, and from K as a centre draw arc S B T. 

A very near approach to the true form of a true 
ellipse may be drawn by the construction given in 
Figure 81, in which A A and BB are centre lines 
passing through the major and minor axis of the 
ellipse, of which a is the axis or centre, <5^ is the major 
axis, and ae half the minor axis. Draw^ the rectangle 
bfgc, and then the diagonalline be; at a right angle 
to be draw Xm^fh, cutting B B at i. With radius a e 
and from ^ as a centre draw the dotted arc ej, giving 



70 



MECHANICAL DRAWING SELF-TAUGHT. 



the point /on line B B. From centre k, which is on 
the line B B and central between b and /, draw the 
semicircle bm j, cutting A A at /. Draw the radius 




Fig. 8i. 
of the semicircle /;;;//, cutting it at ;;/, and cutting/^^ 
at n. With th<i radius ;;/ ;/ mark on A A at ancf from 
(y as a centre the jx.int o. With radius h o and frcim 



LINES AND CURVES. 



71 



centre h draw the arc p q. With radius a I and from 
b and c as centres, draw arcs cutting j?^ q 2X the points 
p q. Draw the Hnes h p r and h q s and also the lines 
pit and q v iv. From h as a centre draw that part 
of the ellipse lying between r and i", with radius^ r ; 
from / as a centre draw that part of the ellipse lying 
between r and t, with radius q s ; and from ^ as a centre 
draw the ellipse from s to zv, with radius i t ; and from i 
as a centre draw the ellipse from tX.o b and with radius 




Fig. 82. 

z^ ze;, and from z/ as a centre draw the ellipse from w 
to <f, and one-half of the ellipse will be drawn. It will 
be seen that the whole construction has been per- 
formed to find the centres h,p, q, /and v, and that while 
e/ and i may be used to carry the curve around on the 
other side of the ellipse, new centres must be pro- 
vided for h p and q, these new centres corresponding 
in position to /// q. Divesting the drawing of all the 



72 



MECHANICAL DRAWING SELF-TAUGHT. 



lines except those determining its dimensions and the 
centres from which the ellipse is struck, we have In 
Figure 82 the same ellipse drawn half as large. The 
centres v, p, q, h correspond to the same centres In Fig- 
ure 81, while z/, p\ q\ >^'are In corresponding positions 
to draw In the other half of the ellipse. The length of 
curve drawn from each centre is denoted by the dotted 
lines radiating from that centre ; thus, from h the part 
from ;^ to ^ Is drawn ; from k that part from r' to /. At 
the ends the respective centres v are used for the parts 
from WX.OU/ and from t to t' respectively. 

The most correct method of drawing an ellipse Is 
by means of an Instrument termed a trammel, which Is 
shown In Figure '^i. It consists of a cross frame in 

B 




which arc two grooves, represented by the broad black 
lines, one of which Is at a right angle to the other. 
In these grooves are closely fitted two sliding blocks, 
carrying pivots E F, which may be fastened to the 
sliding blocks, while leaving them free to slide in the 
grooves at any adjusted distance apart. These blocks 
carry an arm or rod having a tracing point (as pen or 
pencil) at G. When this arm is swept around by the 



LINES AND CURVES. 



73 



operator, the blocks slide In the grooves and the pen- 
point describes an ellipse whose proportion of width 
to length is determined by the distance apart of the 
sliding blocks, and w^hose dimensions are determined 
by the distance of the pen-point from the sliding block. 
To set the instrument, draw lines representing the 
major and minor axes of the required ellipse, and set 
off on these lines (equidistant from their intersection), 
to mark the required length and width of ellipse. 
Place the trammel so that the centre of its slots is 
directly over the point or centre from which the axes 
are marked (which may be done by setting the centres 
of the slots true to the lines passing through the axis) 
and set the pivots as follows : Place the pencil-point 
G so that it coincides with one of the points as C, and 
place the pivot E so that it comes directly at the point 
of intersection of the two slots, and fasten it there. 
Then turn the arm so that the pencil-point G coincides 
with one of the points of the minor axis as D, the arm 
lying parallel to B D, and place the pivot F over the 
centre of the trammel and fasten it there, and the 



setting is complete. 



^ ^^^^^^^mmmmmpmm^^&smmm^^^" I »> 




Fig. 84. 

To draw a parabola mechanically: In Figure 84 
C D is the width and H J the height of the curve. 



74 



MECHANICAL DRAWING SELF-TAUGHT. 



Bisect H D In K. Draw the diagonal line J K and 
draw K E, cutting K at a right angle to J K, and pro- 
duce it In E. With the radius H E, and from J as a 
centre, mark point F, which will be the focus of the 
curve. At any convenient distance above J fasten a 
straight-edge A B, setting it parallel to the base C D 
of the parabola. Place a square S with its back 
against the straight-edge, setting the edge O N coin- 
cident with the line J H. Place a pin in the focus F, and 
tie to it one end of a piece of twine. Place a tracing- 
point at J, pa^s the twdne around the tracing-point, bring- 
ing down along the square-blade and fasten it at N, with 
the tracing-point kept against the edge of the square 
and the twine kept taut ; slide the square along the 
straight-edge, and the tracing-point will mark the half 
J C of the parabola. Turn the square over and 
repeat the operation to trace the other half J D. 
This method corresponds to the method of draw- 
ing an ellipse by the twine and pins, as already de- 
scribed. 

To draw a parabola by lines : Bisect the width A B 
in Figure 85, and divide each half into any convenient 



P |__|_|_^_L_,,,^ I |^>^^4~^._ l l| g 



Fig. 85. 

number of equal divisions ; and through these points 
of division draw vc^rtical lines, as i, 2, 3. etc. (in each 
half). Divide tlie hclglit A D at one end and B E at 
the other into as many equal divisions as the half of 



LINES AND CURVES. y^ 

A B is divided into. From the points of divisions i, 
2, 3, etc., on lines A D and B E, draw lines pointing to 
C, and where these lines intersect the corresponding- 
vertical lines are points through which the curve may 
be drawn. Thus on the side A D of the curve, the 
intersection of the two lines marked i is a point in the 
curve ; the intersection of the two lines marked 2 is 
another point in the curve, and so on. 

TO DRAW A HEART CAM. 

Draw the line A B, Figure 86, equal to the length 
of stroke required. Divide it into any number of 




Fig. 86. • 

equal parts, and from C as a centre draw circles 
through the points of division. Draw the outer circle 
and divide its circumference into twice as many equal 
divisions as the line A B was divided into. Draw 
radial lines from each point of division on the circle, 
and the points of intersection of the radial lines with 
the circles are points for the outline of the cam, and 



^5 MECHANICAL DRAWING SELF-TAUGHT. 

through these points a curved Hne may be drawn giv- 
ing the shape of the cam. It is obvious that the 
ereater the number of divisions on A B, the more ) 

points and the more perfect the curve may be 
drawn. 



CHAPTER IV. 



SHADOW LINES AND LINE SHADING, 



SECTION LINING OR CROSS-HATCHING. 

When the interior of a piece is to be shown as a 
piece cut in haH', or when a piece is broken away, as is 
done to make more of the parts show, or show more 
clearly, the surface so broken away or cut off is sec- 
tion-lined or cross-hatched : that is to say, diagonal 




Fig. 87. 

lines are drawn across it, and to distinguish one piece 
from, another these lines are drawn at varying angles 
and of varying widths apart. In Figure 87 is given a 
view of three cylindrical pieces. It may be known to 
be a sectional view by the cross-hatching or section 
lines. It would be a difficult matter to represent the 
three pieces put together without showing them in 
section, because, in an outline view, the collars and re- 

(77) 



78 



MECHANICAL DRAWING SELF-TAUGHT. 



cesses would not appear. Each piece could of course 
be drawn separately, but this would not show how they 
were placed when put together. They could be shown 
in one view if they were shaded by lines and a piece 
shown broken out where the collars and recesses are, 
but line shading is too tedious for detail drawings, 
beside involving too much labor in their production. 

Figure 88 represents a case in which there are 
three cylindrical pieces one within the other, the two 






Fig. ^^. 



Fig. 89. 



inner ones being fastened together by a screw which 
is shown dotted in in the end view, and whose position 
along the pieces is shown in the side view. The 
edges of the fracture in the outer piece are in this case 
cross-hatched, to show the line of fracture. 

In cross-hatching it is better that the diagonal lines 
do not quite meet the edges of the piece, than that 
they should in the least overrun, as is shown in Fig. 
ure 89, where in the top half the diagonals slightly 
overrun, while in the lower, half they ([o not quit(.' 
meet tlie oudines of the piece. 

In Figure 90 an^ shown in section a number ot' 
pieces one within tlic other, tli<' < .-niral bon^ bein^- 



SHADOW LIXES AXD LINE SHADING. 



79 



filled with short plugs. All the cross-hatching was 
done with the triangle of 60 degrees and that of 90 
degrees. It is here shown that with these two tri- 
angles only, and a judicious arrangement of the di- 




Fig. 90. 

agonals, an almost infinite number of pieces may be 
shown in cross section without any liability of mistak- 
ing one for the other, or any doubt as to the form and 
arrangement of the pieces ; for, beside the difference 
in spacing in the cross-hatching, there are no two ad- 
joining pieces with the diagonals running in the same 
direction. It will be seen that the narrow pieces are 
most* clearly defined by a close spacing of the cross- 
hatchinor. 

In Figure 91 are shown three pieces put together 
and having slots or keyways through them. The 
outer shell is shown to be in one piece from end to 
end, because the cross-hatching is not only equally 
spaced, but the diagonals are in the same direction ; 
hence it would be known that D, F, H, and E were 
slots or recesses through the piece. The same re- 
marks apply to piece B, wherein G, J, K are recesses 



8o 



ME CHA NIC A L DRA WING SELF- TA VGIIT. 



or slots. Piece C is shown to have in its bore a recess 
at L. In the case of B, as of A, there would be no 
question as to the piece being all one from end to 
A 

B 
C 




Fig. 91. 

end, notwithstanding that the two ends are completely 
severed where the slots G, I, come, because the 
spacing and direction of the cross-hatching are equal 
on each side of the slots, which they would not be if 
they were separate pieces. 




Fig. 92. 

Section sliacling or cross-hatching niay sometimes 
(.iiise the lines of tlie drawing to appear crooked to 
the eye. Thus, in Mgure 92, the key edge on the 
) : ;ht aj)pears nirvixl inwards, while on tlu; Ic ft 



SHADO IV LINES AND LINE SHADING. gi 

the key edge appears curved outwards, although such 
is not actually the case. The same effect is produced 




Fig. 93. 

in Figure 93 on the right-hand edge of the key, but 
not on the left-hand edoe. 




Fig. 94. 

A remarkable instance of this kind is shown in 
Figure 94, when the vertical lines appear to the eye 
to be at a considerable angle one to the other, although 
they are parallel. 

The lines in sectional shading or cross-hatchincr 
may be made to denote the material of which the 



82 



MECHANICAL DRAWING SELF-TAUGHT. 



piece is to be composed. Thus Professor Unwin has 
proposed the system shown in the Figures 95. and 96. 
This may be of service in some cases, but it would 




Lead. 



Wood. 



Steel. 



Fii 



95- 



involve very much more labor than it is worth in 
ordinary machine shop drawings, except in the case 
of cast iron and wood, these two beino- shown in the 




Brass. Wrought Iron. Cast Iron, 

Fig. 96. 

simplest and the usual manner. It is much better to 
write the name of the material beneath the piece in a 
detail drawing. 

LINE SHADING. 

Mechanical drawdnes are made to look better and 
to show more distinctly by being line shaded or 
shaded hy lines. The simplest form of line shading 
is by the use of the shade or shadow line. 

In a meclianical drawing the light is supposed, for 
the purpose's of line shading or of coloring, to come 
in from LJic ui>p(r h^t-hand corner of the drawing 
j).iper; hence it falls directly upon tlie upper and left- 
1, .i,.1 Imv^ <»r '•;•< 1> piece, which are therefore; repre- 



SHADOW LINES AND LINE SHADING. 



S3 



seated by fine lines, while the right hand and lower 
edges of the piece being on the shadow side may 
therefore, with propriety, be represented by broader 
lines, which are called shadow or shade lines. These 
lines will often serve to Indicate the shape of some 





Fig. 97. 



Fig. 98. 



part of the piece represented, as will be seen from the 
following examples. In Figure 97 is a piece that 
contains a hole, the fact being shown by the circle 




Fig. 99. 

belnf)^ thickened at A. If the circle were thickened on 
the other side as at B, in Figure 98, it would show 
that it represented a cylindrical stem instead of a hole. 



In Fignrr- 



99 is represented a n^asher, the surfaces 



84 



MECHANICAL DRAWING SELF-TAUGHT. 



that are in the shadow side being shown in a shade 
line or shadow Hne, as it is often called. 

In Figure loo is a key drawn with a shade line, 



A 




Fig. loo. 



Fi! 



lOI. 



Fig. 



while in Figure loi the shade line is shown applied 
toa nut. The shade line may be produced in straight 
lines by drawing the line twice over, and slightly in- 
clining the pen, or by opening the pen points a litde. 
For circles, however, it may be produced either by 
slighdy moving the centre from which the circle is 
drawn, or by going over the shade part twice, and 
sHghtly pressing the instrument as it moves, so as to 
gradually spring the legs farther apart, the latter plan 
being generally preferable. 

Figure 102 shows a German pen, that can be regu- 
lated to draw linc.'s of various breaddis. The head of 
the adjusting screw is made rather larger than usual, 
and is divided at th(i under side into twenty divisional 
notches, each alternate notch being marked by a figure 



SHADOW LIXES AND LINE SHADING. 85 

on the face. By this arrangement a uniform thickness 
of line may be maintained after filling or clearing the 
pen, and any desired thickness may be repeated, with- 
out any loss of time in trial of thickness on the paper. 
A small spring automatically holds the divided screw- 
head in any place. With very little practice the click 
of the spring in the notches becomes a sufficient guide 
for adjustment, without reference to the figures on the 
screw-head. Another meritorious feature of this pen 
is that it is armed with sapphire points, which retain 
their sharpness very long, and thus save the time and 
labor required to keep ordinarv instruments in order 
for the performance of fine work. 

An example of line shading in perspective drawing* 
is shown in the drawing of a pipe threading stock and 
die in Figure 103. 




Fig. 103. 

Shading by means of lines may be used with excel- 
lent effect in mechanical drawing, not only to distin- 
guish round from flat surfaces, but also to denote to 
the eye the relative distances of surfaces. 'Figure 104 



S6 



MECHANICAL DRAWING SELF-TAUGHT. 



represents a cylindrical pin line shaded. As the light 
is supposed to come in from the upper left-hand corner, 
it will evidently fall more upon the left-hand half of 





Fig. 104. 



Fig. 105. 



.the stem, and of the collar or bead, hence those parts 
are shaded with lighter or finer lines than the right- 
hand sides are. . 

Two cylindrical pieces that join each other may be 
line shaded at whatever angle they may join. Figure 
105 represents two such pieces, one at a right angle 
to the other, both being of equal diameter. 

Figure 106 represents a drawincr of a lathe centre 




Fig. 106. 

shaded by lines, the lines on the taper parts meeting 
those on the parallel part A, and becoming more 
nearly parallel to the axis of the piece as the centre 
of the piece is approached. Th(* same is the case 
where a piece having a curved outline is drawn, which 
is shown in Figure 107, where the set of the bcnv-pen 



SHADOW LIXES AXD LI.VE SJIADl.XG. 



87 



is gradually increased for drawing the shade lines of 
the curves. The centres of the shade curves fall in 
each case upon a line at a right angle to the axis of 




Fig. 107. 

the piece, as upon the lines A, B, C, the dotted lines 
showinof the radius for each curve. 

The lines are made finer by closing the pen points 
by means of the screw provided for that purpose. 
The pen requires for this purpose to be cleaned of 
the ink that is apt to dry in it. 

In Figure 108 line shading is shown applied to a 
ball or sphere, while in Figure 109 it is shown ap- 
plied to a pin in a socket which is shown in section. 
By showing the hollow in connection with the round 
piece, the difference between the two is quite clearly 



88 



MECHANICAL DRAWING SELF- TAUGHT. 



seen, the light falling most upon the upper half 
of the pin and the lower half of the hole. This 




Fig. io8. 

perhaps is more clearly shown in the piece of 
tube' in Figure no, where the thickness of the tube 
showing is a great aid to the eye. So, likewise, the 







^'M^^MMM^. 


^^ 






W 


— 1 


m 


'mmm. 


^liP 


P 



Fig. 109. 

hollow or hole is more clearly seen where the piece is 

shown in section, as in Figure iii, which is the case 

even though the piece be taper as in the figure. If 

the body be bell-mouthed, as 

in Figure 112, the hollow 

curve is readily shown by 

die shading ; but to line shade 

a hollow curve without any 

of these aids to the eye, as ^^^S- ^'°- 

say, to show a half of a tin lube, is a very difficult 




SHADOW LINES AND LINE SHADING. 



89 





Fig. III. 

matter If the piece is to look natural; and all that can 

be done is to shade the top 

darkly and let the light fall 

mostly at and near the bottom. 

An example of line shading to 

denote the relative distances 

from the eye of various surfaces 

is given in Figure 113, where 

the surfaces most distant are the -r^- _^ 

rig. 112. 

most shaded. The flat surfaces 

are lined with lines of equal breadth, the degrees of 







"Lr 



Fig. 113. 

shadino- being governed by the width apart of the 
lines. 



90 



MECHANICAL DRAWING SELF-TAUGHT. 



Line shading is often used to denote that the piece 
represented is to be of wood, the shade lines being in 




Fig. 114. 

some cases regular in combination with regular ones, 
or entirely irregular, as in Figure 114. 



CHAPTER V. 



MARKING DIMENSIONS. 



The dimensions of mechanical drawino^s are best 
marked in red ink so that they will show plainly, and 
that the lines denoting the points at which the dimen- 
sion is given shall not be confounded with the lines 
of the drawing. 

The dimension figures should be as large as the 
drawing will conveniently admit ; and should be marked 
at every point at which a shoulder or change of form 
or dimension occurs, except in the case of straight 
tapers which have their dimensions marked at each 
end of the taper. 

In the case of a single piece 
standing by itself the dimension 
figures may be marked all stand- 
in or one way, so as to be read 
without changing the position of 
the operator or requiring to turn 
the drawing around. This is 
done in Figure 115, which repre- 
sents the drawing of a key. The 
figures are here placed outside 
the drawinor in all cases where it 
can be done, which, in the case 
of a small drawing, leaves the Fig. 115. 

same clearer. (91) 



92 



MECHANICAL DRAWING SELF-TAUGHT. 



In Figure ii6 the dimensions are marked, running 
parallel to the dimension for which they are given, so 



jn 



~f I 



4 



--H- 



Fig. ii6. 

that all measures of length stand lengthwise, and those 
of breadth across the drawing. 

Figure 1 1 7 represents a key with a sharp-cornered 
step in it. Here the two dimensions forming the 







1 









"1- 



.% 



Fig. 117. 

steps cannot both be coincident with it; hence they 
are marked as near to it -as convenient, it being un- 
derstood that they apply to the step, and not to one 
side of it. When the step has a round instead of a 
sharp corner, the radius of the arc of the corner may 
be marked, as shown in Figure 1 18. 

Figure 119 represents a key drawn in perspective, 



MARKING DIMENSIONS. 



93 



SO that all the dimensions may be marked on one 
view. Perspective sketches may be used for single 
pieces, as they denote the shape of the piece more 









V 1 

\ 4 




35 


*, 


■^ 





^ 1 " 




^^IL^ 



Fig. 1 1 8. 

clearly to the eye. On account of the skill required 
in their production, they are not, however, used in 
mechanical drawing, except as in the case of Patent- 




Fig. 119. 

Office or similar drawings, where the form and con- 
struction rather than the dimension is the Information 
sought to be conveyed. 



CHAPTER VI. 
IM ARRANGEMENT OF DIFFERENT VIEWS. 

THE DIFFERENT VIEWS OF A MECHANICAL DRAWING. 

The word elevation, as applied to mechanical draw- 
ing, means simply a view; hence a side elevation is a 
side view, or an end elevation is an end view. 

The word plan is employed in place of the word 
top; hence a plan view is a top view, or a view look- 
ing down upon the top of the piece. 

A e^7zeral v\Q\N means a view showino^ the machine 
put together or assembled, while a detail drawing is 
one containing a detail, as a part of the machine or a 
single piece disconnected from the other parts of the 
whole machine. 

It is obviously desirable in a mechanical drawing to 
present the piece of work in as few views as possible, 
but in all cases there must be a sufficient number to 
l^ermit of the dimensions in every necessary direction 
to be marked on the drawing. Suppose, then, that 
in Figure 120 we have to represent a solid cylinder, 
whose length equals its diameter, and it is obvious 
tliat both the diameter and length may be marked in the 
one view given; hence, a second view, such as shown 
])y the circle in Figure 121, is unnecessary, except it 
be to distinguish the body from a cube, in which the 

(04) 



THE ARRANGEMEXT OF DIFFEREXT VIEIVS. 



95 



one view would also be sufficient whereon to mark all 
the dimensions necessar}' to enable the piece to be 
It happens, however, that a cube and a cylin- 



mad( 




Jrii;. I 20. 



Fis:. 121. 



der are the only two figures upon which all the di- 
mensions can be marked on one vievv^ of the piece, 
and as cylindrical pieces are much more common in 
machine work than cubes are, it is taken for granted 
that, where the pieces are cylindrical, but one view shall 
be used, and that where they are cubes either two 
views shall be given, or where they are square a cross 
shall be marked upon the parts that are square ; 
thus, in Figure 122, is shown a cross formed by the 
lines A B across the face of the drawing, which saves 
making- a second view. 





It would appear that under some conditions this 
might lead to error; as, for example, take the piece in 
Figure 12^, and there is nothino- to denote which is 



g(3 MECHANICAL DRAWING SELF-TAUGHT. 

the length and which Is the diameter of the piece, but 
there is a certain amount of custom in such cases that 
will usually determine this point; thus, the piece will 
be given a name, as pin or disk, the one denoting that 
its diameter is less than its length, and the other that 
its diameter is greater than its length. In the absence 
of any such name, it would be in practice assumed 
that it was a pin and not a disk; because, if it were a 
disk, it would either be named or shaded, or a second 
view given to show its unusual form, the disk being a 
more unusual form than the pin-form in mechanical 
structures. As an example of the use of the cross to 




a 





Fig. 124. 

denote a square, we have Figure 124, which repre- 
sents a piece having a hexagon head, section a, a\ 
that is rectangular, a collar b, a square part r, and a 
round stem d. Here it will be noted that it is the 
rectangular j)art a, a\ that renders necessary two views, 
and that in the absence of the cross, yet another view 
would be necessary to show that part c is square. 
A rectangular piece always requires two views and 



THE ARRANGEMENT OF DIFFERENT VIEWS. 



97 



sometimes three. In Figure 125, for example, is a 
piece that would require a side view to show the 





Fig. 126. Fig. 127. 

length and breadth, and an edge view to show the 
thickness. Suppose the piece to be wedge-shaped In 
any direction; then another view will be necessary, a-s 
is shown in Figs. 126 and 127. In the former the 




Fig. 128. 

wedge or taper is in the direction of Its length, while 
in the latter it is In the direction of its thickness. 
Outline views, however, will not in some cases show 
the form of the figure, however many views be 
7 



q3 mechanical drawing self-taught. 

presented. An example of this is given in Figure 
1 28, which represents a ring having a hexagon cross 
section. A sectional edge view is here necessary in 




Fig. 129. 

order to show the hexagonal form. Another example 
of this kind, which occurs more frequently in practice, 
is a cupped ring such as shown in Figure 1 29. 

EXAMPLES. 

Let it be required to draw a rectangular piece such 
as is shown in two views in Figure 130, and the pro- 
cess for the pencil lines is as follows: 



iUdcViru' 



End 



Fig. 130. 



With the bow-pencil set to half the required length 
and breadth of the scjuarc the arcs i, 2, 3 and 4, in 
Mgure 131, an: marked, and then the lines s and 6, 



THE ARRANGEMENT OF DIFFERENT VIEWS, 



99 



letting them run past the width of the arcs 3 and 4. 
There is no need to pencil in Hnes 7 and 8, since they 
can be inked in without pencilHng, because it is 
known that they must meet the arcs 3 and 4 and ter- 




Fig. 131, 

minate at the lines 5 and 6. The top and bottom 
lines of the edge view are merely prolongations of 
lines 5 and 6; hence the lines 9 and 10 are drawn the 
requisite distance apart for the thickness and to meet 
the top and bottom lines. The lines are then inked 
in, the pencil lines rubbed out, and the drawing will 
appear as in Figure 130. 




End View Side View 

Fig. 132. 

Suppose, however, that the piece has a step in it, as 
in F'igure 132, and the pencilling will be as in Figure 
133. From the centre, the arcs i, 2, 3 and 4 for the 
outer, and arcs 5, 6, 7 and 8 for the inner square are 
marked; lines 9 and 10, and their prolongations, 11 



lOO 



MECHANICAL DRAWING SELF-TAUGHT. 



and 12, for the edge view, are then pencilled; lines 
13 and 14, and their prolongations, 15 and 16, are then 
pencilled, and dots to show the locations for lines 21 
and 22 maybe marked and the pencilling is complete. 



17 



13 



18 



19 



14 



21 



22 



20 



16 



23 



10 



12 



Fig. 133. 

Lines 17, 18, 19, 20, 21, 22, and 23 may then be 
inked in, in the order named, and then lines 9, 10, 
II, 12, 13, 14, 15 and 16, when the inking in will be 
complete. 

In inking in horizontal lines begin at the top and 
mark in each line as the square comes to it; and in 
inking the vertical ones begin always at the left hand 
line and mark the lines as they are come to, moving 
the square or the triangle to the right, and great 
care should be taken not to let the lines cross where 
they meet, as at the corners, since this would greatly 
impair the appearance of the drawing. , 

These figures have been drawn without the aid of 
a centre line, because from their shapes it was easy 
to dispense witli it, but in most cases a centre line is 
necessary; tluis in Figure 1 34 we have a body having a 
number of stejjs. The diameters of these steps are 
marked by arcs, as in the previous examples, and 
iheir lengths may be marked by applying the measur- 
ing rule direct to th(! ch-awing paper and making the 
necessary pencil mark. 



THE ARRANGEMENT OE D IEEE RE NT VIEWS. 



lOI 



But It would be tedious to mark the successive 
steps true one with the other by measuring each step, 
because one step would require to be pencilled in 
before the next could be rriarked. To avoid this the 
centre line i, Figure 134, is first marked, and the arcs 



Side View End View 

Fig. 134. 

for the steps are then marked as shown. Centre lines 
are also necessary to show the alignment of one part 
to another; thus in Figure 135 is a cube with a hole 



Fig. 135- 

passing through it. The dotted lines In the side view 
show that the hole passes clear through the piece 
and is a parallel one, while the centre line, being cen- 
tral to the outline throughout the piece, shows that 
the hole Is equidistant, all through, from the walls of 
the piece. 

The pencil lines for this piece would be marked as 
In Figure 136, line i representing the centre line from 
which all the arcs are marked. It will be noted that 



102 



MECHANICAL DRAWING SELF-TAUGHT. 



the length of the piece is marked by arcs which occur, 
because being a cube the set of the compasses for 
arcs 2, 3, 4 and 5 will answer without altering to 
mark arcs 6 and 7. 



^ 5 - 






\C:\\ 


6 7^ 


1 


> v.y ' 






~^4_ 







End View 



Side yiew 



Fig. 136. 



If the hole in the piece were a taper or conical one, 
it would be denoted by the dotted lines, as in Figure 
137, and that the taper is central to the body is shown 




Fig. 137. 

by these dotted lines being equidistant from the cen- 
tre line. 

Suppose one of the sides to be tapered, as is the 
side A, in Figure 138, and that the hole is not central, 
and both facts will be shown by the centre lines i 
and 2 in the figure. The measurement of face A 
would be marked from A to line B at each end, but 
the distance die hoh^ was out of the centre would be 



THE ARRANGEMENT OF DIFFERENT VIEWS. 



103 



marked by the distance between the centre line 2 
and the edge C of the piece. 

A 




Fig. 138. 

If the hole did not pass entirely through the piece, 
the dotted lines would show it, as in Figure 139. 




Fig. 139. 

The designations of the views of a piece of work 
depend upon the position in which the piece stands, 





I04 



ME CHA hUCA L DKA WING SELF- TA UGHT. 



when In place upon the machine pf which it forms 
a part. Thus in Fi^^ure 140 is a lever, and if its shaft 
stood horizontal when the piece is in place in the 




Fig. 141. 

machine, the view given is an end one, but suppose 
that the shaft stood vertical, and the same view^ be- 
comes a plan or top view» 



1 r. 



A 



^ 



Fig. 142. 



THE ARRANGEMENT OF DIFFERENT VIEWS. 



105 



In Figure 142 Is a view of a lever which is a side 
view if the lever stands horizontal, and lever B hangs 
down, or a plan view if the shaft stands horizontal, 
but lever B stands also horizontal. We may take the 
same drawing and turn it around on the paper as in 
Figure 143, and it becomes a side view if the shaft 
stands vertical, and a plan view if the shaft stands hori- 
zontal and arm D vertical above it. 

In a side or an end view, the piece that projects 
highest in the drawing is highest when upon the 



T 



^ 



Fig. 143- 

machine ; also in a side elevation the piece that is at 
the highest point in the drawing extends farthest 
upward when the piece Is on the machine. But in 
a plan or top view the height of vertical pieces is 
not shown, as appears in the case of arm D In Figure 

143- 

In either of the levers, Figures 142 or 143, all the 

dimensions could be marked if an additional view 

were given, but this will not be the case if an eye 



;o6 



MECHANICAL DRAWING SELF-TAUGHT. 



have a slot in It, as at E, In Figure 144, or a jaw have 
a tongue in it, as at F : hence, end views of the eye 
and the jaw must be given, which may be most con- 
veniently done by showing them projected from the 
ends of those parts as in the figure. 

This naturally brings us to a consideration as to 
the best method of projecting one view from another. 



e>t^ view ofj^ 




Fig. 144. 

As a general rule, the side elevation or side view is 
the most Important, because It shows more of the 
parts and details of the work ; hence it sliould be 
drawn first, because it affords more assistance In 
drawinof the other views. 

There are two systems of placing the different views 



THE ARRANGEMENT OF DIFFERENT VIEWS. 107 

of a piece. In the first the views are presented as the 
piece would present itself if it were laid upon the paper 
for the side view, and then turned or rolled upon the 
paper for the other views, as shown in Figure 145, 
in which the piece consists of five sections or mem- 
bers, marked respectively A, B, C, D, and E. Now if 
the piece were turned or rolled so that the end face 



S D 

I 
1 
1 

2 D 




^ 


A 


j 








B 








1 A 






c 




E 


! 


i 
1 
1 


B 


c 



A 

Fig. 145- 

of B were uppermost, and the member E was beneath, 
it will, by the operation of turning it, have assumed 
the position in the lower view marked position 2 ; 
while if it were turned over upon the paper in the 
opposite direction it would assume the position 
marked 3. This gives to the mind a clear idea of 



I08 



MECHANICAL DRAWING SELF-TAUGHT. 



the various views and positions; but it possesses some 
disadvantages: thus, if position i is a side elevation or 
view of the piece, as it stands when in place of the 
machine, then E is naturally the bottom member; but 
it is shown in the top view of the drawing, hence what 
is actually the bottom view^ of the piece (position 3) 
becomes the top view in the drawing. A second dis- 
advantage is that if we desire to put in dotted lines, 



IG 



D 

i 

i 

1 
D 

1 


e 


C 


! 

B 




A 


c 


1 


h 


1 1 
1 1 
1 1 

1 1 


D 


1 ] 

(!) 

A 


c 



Fig. 146. 
to show how one view is derived from the other, and 
denote corresponding parts, then these dotted lines 
must be drawn across the face of the drawing, making 
it less distinct; thus the dotted lines connecting stem 
]^^ in position i to E in position 3, pass across the faces 
of both A and W of position i. 

In a large drawing, or one composed of many mem- 
bers or parts, it would, therefore, be out of the ques- 



THE ARRANGEMENT OF DIFFERENT VIEWS. 109 

tion to mark in the dotted lines. A further disadvan- 
tage in a large drawing is that it is necessary to go 
from one side of the drawinor to the other to see the 
construction of the same part. 

To obviate these difficulties, a modern method is to 
suppose the piece, instead of rolling upon the paper, 
to be lifted from it, turned around to present the re- 




A 



Fig. 147. 
quired view, and then moved upwards on the paper 
for a top view, sideways for a side view, and below 
for a bottom view. Thus the three views of the piece 
in Figure 145 would be as in Figure 146, where posi- 
tion 2 is obtained by supposing the piece to be lifted 
from position i, the bottom face turned uppermost, 
and the piece moved down the paper to position 2, 



no 



MECHANICAL DRAWING SELF-TAUGHT. 



which Is a bottom view of the piece, and the bottom 
view in the drawing. Similarly, if the piece be lifted 
from position i, and the top face in that figure is 
turned uppermost, and the piece is then slid upwards 
on the paper, view 3 Is obtained, being a top view of 
the piece as It lies in position i, and the top view in 
the drawing. Now suppose we require to find the 



o::: 



Al 



© 



Fig. 148. 

shape of member B, then in Figure 145 we require to 
look at the top of position i, and then down below to 
j)osition 2. 

But in Figure 146 we have the side view and end 
view both togc^dier, while the dotted lines do not re- 
quire to cross the face of the side view. Now sup- 



THE 'ARRANGEMENT OF DIFFERENT VIEWS. i 1 1 

pose we take a similar piece, and suppose its end 
faces, as F, G, to have holes in them, which require to 
be shown in both views, and under the one system the 
dravv^ing would, if the dotted lines were drawn across, 
appear as in Figure 147, whereas under the other 
system the drawing would appear as in Figure 148. 
And it follows that in cases where it is necessary to 
draw dotted lines from one view to the other, it is 
best to adopt the new system. 



CHAPTER VII. 

EXAMPLES IN BOLTS, NUTS, AND POLYGONS, 

Let it be required to draw a machine screw, and it 
is not necessary, and therefore not usual in small 
screws to draw the full outline of the thread, but to 
represent it by thick and thin lines running diagonally 
across the bolt, as in Figure 149, the thick ones repre- 






Fig. 150. 



Fig. 151 



Fig. 149. 

sendng the bottom, and the thin ones the top of the 
thread. The pencil lines would be drawn in the order 
shown in Figure 150. Line i is the centre line, and 
line 2 a line to represent the lower side of the head ; 
from the intersection of these two lines as a centre (as 
at A) short arcs 3 and 6, showing the diameter of the 
thread, are marked, and the arcs $ and 6, representing 
the depth of the thread, are marked. The arc 7, rep- 
resenting tlic head, Is then marked. The vertical 
lines 8, 9, 10, and 11 are then marked, and the out- 
line of the screw is (omplcte. The thick lines repre- 
(112) 



EXAMPLES IN BOLTS, NUTS, AND POLYCGXS. 



113 



senting the bottom of the thread are next marked in, 
as in Figure 151, extending from Hne 9 to Hne 10. 
Midway between these lines fine ones are made for 
the tops of the thread. All the lines being pencilled 
in, they may be inked in with the drawing instruments, 
taking care that they do not overrun one another. 
When the pencil lines are rubbed out, the sketch wdll 
appear as in Figure 149. 

For a bolt with a hexagon head the lines would be 
drawn in the order shown in Figure 152. At a right- 




Fig. 152. 

angle to centre line i, line two is drawn. The pencil- 
compasses are then set to half the diameter of the 
bolt, and from point A arcs 3 and 6 are pencilled, thus 
showing the width of the front flat of the head, as well 
as the diameter of the stem. F>om the point where 
these arcs meet line 2, and with the same radius, arcs 
5 and 6 are marked, showing the widths of the other 



11^ MECHANICAL DRAWING SELF-TAUGHT. 

two flats of the head. The thickness of the head and 
the length of the bolt head may then be marked either 
by placing a rule on line i and marking the short lines 
(such as line 7) a cross line i, or the pencil-compasses 
may be set to the rule and the lengths marked from 




Fig. 153- 
point A. In the United States standard for bolt heads 
and nuts the thickness of the head is made equal to 
the diamoter of the bolt. With the compasses set for 
the arcs 3 and 4, we may in two steps, from A along 
the centre line, m.nk off the thickness of the head 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. n^ 

without using the rule. But as the rule has to be 
applied along line i to mark line 7 for the length of 
the bolt, it is just as easy to mark the head thickness 
at the same time. The line 8 showing the length of 
the thread may be marked at the same time as the 
other lengths are marked, and the outlines 9, 10, 11, 
12, 13 may be drawn in the order named. We have 
now to mark the arcs at the top of the flats of the 
head to show the chamfer, and to explain how these 
arcs are obtained we have in Figure 153 an enlarged 
view of the head. It is evident that . the smallest 
diameter of the chamfer is represented by the circle A, 
and therefore the length of the line B must equal A. 
It is also evident that the outer edge of the chamfer will 
meet the corners at an equal depth (from the face of the 
nut) , as represented by the line C C, and it is obvious that 
the curves that represent the outline of the chamfer 
on each side of the head or nut will approach the face 
of the head or nut at an equal distance, as denoted 
by the line D D. It follows that the curve must in 
each case be such as will, at each of its ends, meet the 
line C, and at its centre meet the line D D, the centres 
of the respective curves being marked in the figure 
byX. 

It is sufficiently accurate, therefore, for all pracjiical 
purposes to set the pencil on the centre-line at the 
point A in Figure 152 and mark the curve 14, and to 
them set the compasses by trial to mark the other 
two curves of the chamfer, so that they shall be an 
equal distance with arc 14 from line 9, and join lines 
10 and 13 at the same distance from line 9 that 14 joins 
lines 3 and 4, so that as in Figure 153 all three of 



ii6 



MECHANICAL DRAWING SELF-TAUGHT. 



the arcs would touch a Hne as C, and another Hne 
as D. 

The United States standard sizes for forcred or un- 



UC9 



•_-D_^ 



1^.J- 




y -r A 



irD-> 



r 



k — ^- 



Fig. 154- 
finished bolts and nuts are criven in the followinor table, 
I'i^il^ure 154 showing the dimensions referred to in the 
table. 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. 117 

tjnitp:d states standard dimensions of dolts and nuts. 



Bolt. 


Bolt Head and Xut. j 




Diameter. 




Long diameter, /, 
or diameter across 


Hi 


i 


>;-5 


^ i 




t 1 1 


corners. | 


E! 3 — 


"S 


3" 


^ 


w 


ET ^ 






p §1' 


=?- 





1- 
















3 


T 


p^ 


n 


Q. ^ i 


p 
en 


p 


Ci^ 


S 


~- 


f;^ 


.*■ 





3 


■ 




?:? 


p 


} 


.185 


20 


fV 


U 


i 1 


i 


i 


tV 


.240 


18 


ii 


U 


M 


tV 


M 


i 


.294 


16 


M 


u 


ii 


f 


M 


r\ 


.345 


14 


§1 


l/l 


2 A 

3 2 


tV 


M 


i 


.400 


13 


1 


1^ 


8 


i 


tV 


T% 


.454 


12 


U 


If 


3i 


T^F 


U 


5 


.507 


11 


!/■? 


U 


liV 


f 


H 


f 


.620 


10 


lA 


U 


li 


f 


1 


1 


.731 


9 


IH 


Vj 


h\ 


7 

8 


M 


1 


.837 


8 


1| 


2tV 


If 


1 


iii 


li 


.940 


7 


2^ 


2t\ 


1 1 3 

■Its 


li 


!l 


u 


1.065 


7 


StV 


2§* 


2 


u 


1 


If 


1.160 


6 


2i* 


3/j 


2A 


If 


Ib^ 


1* 


1.284 


6 


2:1 


3ii 


2t 


1* 


if\ 


If 


1.389 


5} 


nh 


3^ 


2t\ 


11 1 


ift 


If 


1.491 


5 


«fV 


3* 


21 


11 


If 


ll 


1.616 





318 


^\ 


m 


li i 


m 


2 


1.712 


4J 


3if 


m 


3J 


2 ! 


lA 


21 


1.962 


4^ 


43V 


m 


3J 


21 


11 


2* 


2.176 


4 


m 


m 


3| 


2i 


lif 


21 


2.426 


; 4 


4§| 


6 


4i 


21 


2^ 


3 


2.629 


i 3^ 


5M 


m 


44 


3 


2t\ 


31 


2.879 


3^ 


5M 


7tV 


5 


3i 


2} 


3^ 


3.100 


3i 


6sV 


VM 


51 


3^ i 


^m 


31 


3.317 


3 


61 


8i 


51 


3f ! 


2i 




3.567 


1 3 


7tV 
7i 


f4 


6i 


4 ! 


3tV 
3i 


"•41*' 


3.798 


1 21 


6} 


41 ! 


U 


4.028 


21- 


7iJ 


nl 


61 


4i ! 


3tV 


41 


4.256 


2f 


81 


m 


7} 


4f i 


3f 


5 


4.480 


2J 


811 


lOM 


71 


• 5 1 


3^f 


51- 


4.730 


! 2i 


9i 


iifV 


8 


5i i 


4 


5} 


4.953 


' 2^ 


9U 


lliJ 


8t 


5^ ' 


4T?r 


51 


5.203 


! 2f 


IOtj^t 


12i 


8i 


5f 1 


41 


6 


5.423 


2\ 


lOM 


1211 


91 


6 i 


4t^ 



* Diameter at the root of the thread. 



II 



MECHANICAL DRAWING SELF-TAUGHT. 



The basis of the Franklin Institute or United States 
standard .for the heads of bolts and for nuts is as fol- 
lows : 

The short diameter or width across the flats is equal 
to one and one-half times the diameter plus \ inch 
for rough or unfinished bolts and nuts, and one and 
one-half times the bolt diameter plus /g inch for fin- 
ished heads and nuts. The thickness is, for rough 
heads and nuts, equal to the diameter of the bolt, 
and for finished heads and nuts l^ inch less. 








Fig. 155. 



Fig. 156. 



The hexagonal or hexagon (af? they are termed In 
th(^ shop) heads of bolts may be presented In two 
ways, as is shown in Figures 155 and 156. 



EXAMPLES IX BOLTS, XUTS, AXD POLYGOXS. ng 

The latter is preferable, inasmuch as it shows the 
width across the flats, which is the dimension that is 
worked to, because it is where the wrench fits, and 
therefore of most importance; whereas the latter gives 
the length of a flat, which is not worked to, except 
incidentally, as it were. There is the objection to the 
view of the head, given in Figure 156, however, that 
unless it is accompanied by an end vieAv it somewhat 
resembles a similar view of a square head for a bolt. 
It may be distinguished therefrom, however, in the 
following points: 

If the amount of chamfer is such as to leave the 
chamfer circle (as circle A, in Figure 153) of smaller 
diameter than the width across the flats of the bolt- 
head, the outline of the sides of the head will pass 
above the arcs at the top of the flats, and there will 
be two small flat places, as A and B, in Figure 156 
(representing the angle of the chamfer), which will 
not meet the arcs at the top of the flats, but will join 
the sides above those arcs, as in the figure; which is 
also the case in a similar view of a square-headed 
bolt. It may be distinguished therefrom, however, 
in the following points : 

If the amount of chamfer is such as to leave the 
chamfer circle (A, Figure 153) of smaller diameter 
than the width across the flats of the bolt-head, the 
outline of the sides will pass above the arc on the 
flats, as is shown in Figure 157, in which the chamfer 
A meets the side of the head at B, and does not, 
therefore, meet the arc C. The length of side lying 
between B and D in the side view corresponds with 
the part lying between E and F in the end vieAv. 



20 



MECHANICAL DRAWING SELF-TAUGHT. 



If we compare fthis head with similar views of a 
square head G, both being of equal widths, and having 
their chamfer circles at an equal distance from the 
sides of the fiats, and at the same angle, we perceive 
at once that the amount of chamfer necessary to give 




the same distance between the chamfer circle and the 
side of the holt (that is, the distance from J to K, 
beinii^ equal to that from L to M), the length of the 
cliamfcr N for the square head so greatly exceeds the 
K-ngth A for th(^ hexagon head that the eye detects 



EXAMPLES IN BOLTS, NUTS,- AND POLYGONS. 12 I 



the difference at once, and is instinctively informed 
that G must be square, independently of the fact 
that in the case of the square head, N meets the arc 
O, while in the hexagon head, A, which corresponds 
to N, does not meet the arc C, which corresponds 
to O. • 

When, however, the chamfer is 
sufficient to meet the flats, as in 
hexagon H, and the square I, in Figure 157, 
chamfer line passes from the chamfer circle' to 



drawn, but just 
the case of the 
the 
the 



side of the head, and the distinction is greater, as will 
be seen by comparing head H with head I, both being 
of equal width, having the same angle of chamfer, and 
an amount just sufficient to meet the sides of the flats. 
Here it will be seen that in the hexagon H, each side 
of the head, as P, meets the chamfer circle A. 
Whereas, in the square head these two lines are 
joined by the chamfer line Q, the figures being quite 
dissimilar. 

Side 
< G -> 



:Fwff 




^-i^^^ 



Side 



Fig. 158. 



It Is obvious that whatever the degree or angle of 
the chamfer may be, the diameter of the chamfer 



122 



MECHANICAL DRAWING SELF-TAUGHT. 



circle will be the same In any view In which the head 
may be presented. Thus, in Figure 158, the line G 
in the side view is In length equal to the diameter of 
circle G, in the end view, and so long as the angle 
of the chamfer Is forty-five degrees, as In all the views 
hitherto given, the width of the chamfer will be equal 
at corresponding points in the different views ; thus 
in the figure the widths A and B in the two views 
are equal. 

If the other view showing a corner of the head In 
front of the head be given, the same fact holds good, 
as Is shown in Figure 159. That the two outside flats 



G- 









Fig. 159- 



should appear In the drawing to be half the width of the 
middle fiat Is also shown In Figure 158, where D and 
E are each half the width of C. Let us now suppose, 
that the chamfer be given some other angle than that 
of 45 degrees, and we shall find that the effect Is to 
alter the curves of the chamfer arcs on the fiats, as Is 
shown In Figure 160, where these arcs E, C, D are 
shown less curved, because the chamfer B has more 
angle to the fiats. As a result, the width or distance 
between the arcs and line G Is different In the 
two views. On this account it is better to draw the 
chamfer at 45 degrees, as correct rc^sults may be ob- 
tained with the least trouble. 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. 123 

If no chamfer at all Is to be given, a hexagon 
head may still be distinguished from a square one, 
providing that the view giving three sides of the head, 



-G- 



\T~\ c r~D 



Side 




:End 



Fig. 160. 



as in Figure 158, is shown, because the two sides D 
and E being half the width of the middle one C, imparts 
the information that it is a hexagon head. If, how- 
ever, the view showing but .two of the sides and a 
corner in front is given, and no chamfer is used, it 
could not be known whether the head was to be hex- 
agon or square, unless an end view be given, as in 
Figure 161. 

If the view showing a full side of the head of a 
square-headed bolt is given, then either an end view 
must be given, as in Figure 162, or else a single view 
with a cross on its head, as in Figure 163, may be 
given. 

It is the better plan, both In square and hexagon 
heads, to give the view In which the full face of a flat 
Is presented, that Is, as In Figures 155 and 163; be- 
cause. In the case of the square, the length of a side 
and the width across the head are both given In that 
view; whereas If two sides are shown, as In Figure 
161, the width across flats is not given, and this Is the 



124 MECHANICAL DRAWING SELF-TAUGHT, 

dimension that is wanted to work to, and not the 



A 

t 







Fig. 162, 



Alt 



iMg. 163. 

llli across corners. In the case of a hexagon the 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. 125 



middle of the three flats is equal in width to the di- 
ameter of the bolt, and the other two are one-half its 
width; all three, therefore, being marked with the same 
set of compasses as gives the diameter of the body of 
the bolt, were as shown in Figure 152. For the width 
across flats there is an accepted standard; hence 
there is no need to mark it upon the drawing, unless 
in cases where the standard is to be departed frorn. 



7 a 



8d 



Fig. 164. 



in which event an end view may be added, or the 
view showing two sides may be given. 

To draw a square-headed bolt, the pencil lines are 
marked in the order shown by figures in Figure 164. 
The inking in is done in the order of the letters a, b, c, 
etc. It will be observed that pencil lines 2, 9, and 10 
are not drawn to cross, but only to meet the lines at 
their ends, a point that, as before stated, should always 
be carefully attended to. 




Fig. 165. 

To draw the end view of a hexagon head, first draw 
a circle of the diameter across the flats, and then rest 



126 



MECHANICAL DRAWING SELF-TAUGHT. 



the triangle of 60 degrees on the blade s of the square, 
as at T I, in Figure 165, and mark the Hues a and b. 
Reverse the triangle, as at T 2, and draw lines c and 




Fig. 166. 

d. Then place the triangle as in Figure 166, and 
draw the lines e and/^ 

If the other view of the head is to be drawn, then 
first draw the lines a and b in Figure 167 with the 
square, then with the 60 degree triangle, placed on 
the square S, as at T i, draw the lines c, d, and turn- 
ing the square over, as at T2, mark lines e andy^ 




Fig. 167. 

If the diameter across corners of a square head is 
given, and it be required to draw the head, the pro- 
cess is as follows: For a view showing one corner in 
front, as in Figure 168, a circle of the given diameter 
across corners is pencilled, and the horizontal centre- 
line a is marked, and the triangle of 45 degrees is 



I 



EXAMPLES EV BOLTS, NUTS, AND POLYGONS. 127 

rested against the square blade S, as in position T i, 
and lines b and c marked, b being marked first ; and 
the triangle is then slid along the square blade to po- 
sition T I, when line c is marked, these two lines just 




Fig. 168. 

meeting the horizontal line a, where it meets the cir- 
cle. The triancrle is then moved to the left, and line 
d, joining the ends of ^ and c, is marked, and by mov- 
ing it still farther to the left to position T 2, line e is 
marked. Lines b, c, d, and e are, of course, the only 
ones inked in. 

If the flats are to lie In the . other direction, the 
pencilHng will be done as in Figure 169. The circle 




Fig. 169. 

is marked as before, and with the triangle placed as 
shown at T I, line a, passing through the centre oi 
the circle, is drawn. By moving the triangle to the 
right -Its edge B will be brought into position to mark 



12^ 



MECHANICAL DRAWING SELF-TAUGHT. 



line <^, also' passing through the centre of the circle. 
All that remains Is to join the ends of these two lines, 
using the square blade for lines c, d, and the triangle 
for e and f, Its position on the square blade being 
denoted at T 3 ; lines y, d, e,f, are the ones inked in. 

For a hexagon head we have the processes, Figures 
170 and 171. The circle is struck, and across it line 




Fig. 170. 

a, Figure 1 70, passing through Its centre, the triangle 
of sixty degrees will mark the sides d, c, and d, e, as 
shown, and the square blade is used {or f,g. 

The chamfer circles are left out of these figures to 
reduce the number of lines and so keep the engraving 




Fig. 171. 

cle^r. Figure 171 shows the method of drawing a 
hexagon head wIkmi the diameter across corners is 



EXAMPLES IX BOLTS, NUTS, AXD POLYGOXS. 129 

given, the lines being drawn in the alphabetical order 
marked, and the triangle used as will now be under- 
stood. 

It may now be pointed out that the triangle may be 
used to divide circles much more quickly than they 
could be divided by stepping around them with com- 
passes. Suppose, for example, that we require to 
divide a circle into eight equal parts, and we may do 
so as in Figure 172, line a being marked from the 





Fig- 173- 

square, and lines b, c and d from the triangle of forty- 
five degrees ; the lines to be inked in to form an oc- 
tagon need not be pencilled, as their location is clearly 
defined, being lines joining the ends of the lines 
crossing the circle, as for example, lines e,f. 

Let it be required to draw a poh'gon having twelve 
equal sides, and the triangle of sixty is used, 
marking all the lines within the circle in Figure 173, 
except a, for which the square blade is used ; the only 
lines to be inked in are such as b, c. In this example 
there is a corner at the top and bottom, but suppose 
it were required that a flat should fall there instead 
of a corner; then all we have to do is to set the square 
9 



I3G 



MECHANICAL DRAWING SELF-TAUGHT. 



blade S at the required angle, as In Figure 174, and 
then proceed as before, bearing in mind that the point 
of the circle nearest to the square blade, straight-edge, 




or whatever the triangle Is rested on. Is always a 
corner of a polygon having twelve sides. 

In both of these examples we have assumed that 
the diameter across corners of the polygon was 




Fig. 175. 

given, but suppose the diameter across the flats were 
given, and the construction is a little more complicated. 
Circle a, a, in iMgure 175, is drawn of the required 
diameter across the (lats, and the lines of division are 



I 



EXAMPLES I.V BOLTS, NUTS, AXD POLYGONS. 131 

drawn across with the trianorle of 60 as before; the 
triangle of 45 is then used to draw the four lines, b, c, 
d, e, joining the ends of lines i, j\ k, /, and touching 
the Inner circle, a, a. The outer circle is then pencilled 
in, touching the lines of division where they meet the 
lines b, c, d, e, and the rest of the lines for the sides of 
the polygon may then be drawn within the outer circle, 
as at g, h. 

It is obvious, also, that the triangle may be used to 
draw slots radiating from a centre, as in Figure i ']6, 




Fig. 176. 

where It is desired to draw a chuck-plate having 6 
slots. The trlano^le of 60 Is used to draw the centre 
lines, a^ b, c^ etc., for the slots. From the centre, the 
arcs e, f, g, h, etc., are marked, showing where the 
centres will fall for describlno- the half circles formlncr 
the ends of the slots. Then half circles, /, /, Jz, /, etc., 
being drawn, the sides of the slots may be drawn in 
with the triangle, and the outer circle and the slots 
inked in. 

If the slots are net to radiate from the centre of 
the circle the process is as follows: 

The outer circle a, Figure i "]"], being drawn^an Inner 
one b Is drawn, Its radius equalling the amount; the 



1^2 MECHANICAL DRAWING SELF-TAUGHT. 

centres of the slots are to point to one side of the 
centre of circle a. The triangle is then used to 
divide the circle into the requisite number of divisions 




c for the slots, and arcs z*,/, are then drawn for the 
lengths of the slots. The centre lines e are then 
drawn, passing through the lines c, and the arcs i,j, 
etc., and touching the perimeter of the inner circle b; 
arcs y^^, are then marked in, and their sides joined 
with the triangle adjusted by hand. All that would 
be inked in black are the outer circle and the slots, but 
the inner circle b and a centre line of one of the 
slots should be marked in red ink to show how the 
inclination of the slot was obtained, and therefore its 
amount. 

For a five-sided figure it is best to step around the 
circumference of the circle with the compasses, but 
for a three-sided one, or trigon, the construction is as 
follows: It will l)c found that the compasses set to 
the radius of n circle will accurately divide it into six 
equal divisions, as Is shown in iMgure 17S; lience 
every other one of these divisions will be the location 
for a corner of a trio on. 



EXAMPLES EX BOLTS, XUTS, AXD POLYGOXS. 133 

The circle being drawn, a line A, 179, Is drawn 
throLiorh Its centre, and from its intersection with the 
circle as at b, here a step on each side is marked as c, d, 





Fig. 178. 



Fig. 179. 



then lines c to d, and c and d to c, where A meets, the 
circle will describe a trigon. If the figure is to stand 
vertical, all that is necessary is to draw the line a 




Fig. t8o. 



vertical, as In Figure 180. A ready method of getdng 
the dimension across corners, across the flats, or the 
length of a side of a given polygon, is by means of 
diagrams, such as shown in the following figures, 
which form excellent examples for practice. 

Draw the hne O P, Figure 181, and at a right angle 
to it the line O B ; divide these two lines into parts of 
one inch, as shown in the cut, which is divided into 



134 



MECHANICAL DRAV/ING ySELF-TAUGHT, 



A 



inches and quarter Inches, and from these points of 
division draw Hnes crossing each other as shown. 



^7 ' 




-/•i •^/2 



Fig. i8i. 

From the point O, draw diagonal lines, at suitable 
angles to the line O P. As shown in the cut, these 
diagonal lines are marked : 

40 degrees for 5 sided figures. 
45 " " 6 

49 " " 7 

52>< " " 8 
55>< " " 9 
But still others could be added for fiofures havincr a 
greater number of sides. 

I. Now it will be found as follcnvs : Half tlu« diam- 



EXAMPLES IX BOLTS, XUTS, AXD POLYGOXS. ly^ 



eter, or the radius of a piece of cylindrical work being 
given, and the number of sides it is to have being 
stated, the length of one side will be the distance 
measured horizontally from the line O B to the diag- 
onal line for that particular number of sides. 

Example. — A piece of work is 2^ inches in diam- 
eter, and is required to have 9 sides : what will be the ' 
length of the sides or flats? 

Now- the half diameter or radius of 2^ inches 
is I Yj^ inches. Then look along the line O B for i J^, 
which is denoted in the cut by figures and the arrow 
A ; set one point of the compasses at A, and the 
other at the point of crossing of the diagonal line with 
the I Yf horizontal line, as shown in the figure at a, 
and from A to a is the leno^th of one side. 

Again: A piece of w^ork, 4 inches in diameter, is 
to have 9 sides : how long will each side be ? 

Now half of 4 is 2, hence from B to ^ is the length 
of each side. 

But suppose that from the length of each side, and 
the number of sides, it is required to find the diameter 
to which to turn the piece ; that is, its diameter across 
corners, and we simply reverse the process thus: A 
body has 9 sides, each side measures || : what is its 
diameter across corners ? 

Take a rule, apply it horizontally on the figure, and 
pass it along till the distance from the line O B to the 
diagonal line marked 9 sides measures |§, which is 
from 1 1^4 on O B to a, and the i ^ is the radius, which, 
multiplied by 2, gives 2^ inches, which is the required 
diameter across corners. 

For any other number of sides the process is just . 



136 MECHANICAL DRAWING SELF-TAUGHT. 

the same. Thus: A body is 35^ inches in diameter, 
and is to have 5 sides : what will be the length of each 
side ? Now half of 3 J^ is i ^ ; hence from i ^ on the 
line O B to the point C, where the diagonal line crosses 
the i^ line, is the length of each of the sides. 

2. It will be found that the length of a side of a 
square being given, the size of the square, measured 
across corners, will be the length of the diagonal line 
marked 45 degrees, from the point O to the figures 
indicating, on the line O B or on the line O P, the 
length of one side. 

Example. — A square body measures 1 inch on each 
side : what does it measure across the corners ? An- 
swer : From the point O, along diagonal line marked 
45 degrees, to the point where it crosses the lines i 
(as denoted in the figure by a dot). 

Again: A cylindrical' piece of wood requires to be 
squared, and each side of the square must measure 
an inch : what diameter must the piece be turned to ? 

Now the diagonal line marked 45 degrees passes 
through the i-inch line on O B, and the inch line on 
O P, at the point where these lines meet ; hence all we 
have to do is to run the eye along either of the lines 
marked inch, and from its point of meeting the 45 de- 
grees line, to the point O, is the diameter to turn the 
piece to. 

There is another way, however, of getting this same 
measurement, which is to set a pair of compasses from 
the line i on O B, to line i on O P, as shown by the 
line 1 ), which is the full diameter across corners. This 
is apparent, because from point O, along line O B, to 
I, thence to the dot, thence down to line i on O P, and 



EXAMPLES EV BOLTS, NUTS, AND POLYGONS. 137 

along that to O, encloses a square, of which either from 
O to the dot, or the length of the line D, is the meas- 
urement across corners, while the length of each side, 
or diameter across the flats, is from point O to either of 
the points i, or from either of the points i to the dot. 




Fig. 182. 

After graphically demonstrating the correctness of 
the scale we may simplify it considerably. In Figure 
182, therefore, we have applications shown. A is a 
hexagon, and if one of its sides be measured, it will 



138 



MECHANICAL DRAWING SELF-TAUGHT. 



be found that it measures the same as alono- line i 
from O B to the diagonal line 45 degrees, which dis- 
tance is shown by a thickened line. 

At lyi, is shown a seven-sided figure, whose diam- 
eter is 3 inches, and radius i ^ inches, and if from the 
point at i^ (along the thickened horizontal line), to 
the diagonal marked 49 degrees, be measured, it will 
be found exactly equal to the length of a side on the 
polygon. 

At C is shown part of a nine-sided polygon, of 2- 
inch radius, and the length of one of its sides will be 
found to equal the distance from the diagonal line 
marked 52^ degrees, and the line O B at 2. 

Let it now be noted that if from the point O, as a 
centre, we describe arcs of circles from the points of 
division on O B to O P, one end of each arc will meet 
the same fio-ure on O P as it started from at O B, as 
is shown in Figure 181, and it becomes apparent that in 
the lenorth of diao^onal line between O and the re- 

o o 

quired arc we have the radius of the polygon. 

Example. — What is the radius across corners of a 
hexa£{on or six-sided ficrure, the lenq-th of a side beinor 
an inch ? 

Turning to our scale we fmd that the place where 
there is a horizontal distance of an inch between the 
diagonal 45 degrees, answering to six-sided figures, is 
along line i (Plgure 182), and the radius of the circle 
enclosing the six-sided body is, therefore, an inch, as 
will b(^ sc;en on referring to circle A. P)Ut it will be noted 
ihat the length o^ diagonal line 45 degrees, enclosed 
b(;tween tlie point O and die arc of circle from i on 
O B to one on () P, measures also an inch. Hence 



EXAMPLES IX BOLTS, XUTS, AXD POLYGOXS. 



139 



we may measure the radius along the diagonal lines 
if we choose. ' This, however, simply serves to de- 
monstrate the correctness of the scale, which, being 
understood, we may dispense with most of the lines, 
arrivlnor at a scale such as shown in Fic^ure 18^ 



O' 



m 




Fig. 183. 

which the length of the side of the polygon Is the dis- 
tance from the line O B, measured horizontally to the 
diagonal, corresponding to the number of sides of the 
polygon. The radius across corners of the polygon 
is that of the distance from O along O B to the hori- 
zontal line, giving the length of the side of the poly- 
gon, and the width across corners for a given length 
of one side of the square, is measured by the length 
of the lines A, B, C, etc. Thus, dotted line 2 shows 



I40 



MECHANICAL DRAWING SELF-TAUGHT, 



the lencrth of the side of a nine-sided figure, of 2- 
inch radius, the radius across corners of the figure 
beine 2 inches. 

The dotted Hne 2^ shows the lencrth of the side of a 
nine-sided polygon, having a radius across corners of 
2}^ inches. The dotted Hne i shows the diameter, 
across corners, of a square whose sides measure an 
inch, and so on. 

This scale lacks, however, one element, in that the 
diameter across the flats of a regular polygon being 




i^nven, it will not give tlie diameter across the corners. 
'1 liis, however, wc may obtain by a somewhat simi- 
lar construction. Thus, in Figure 184, draw the line 
() B, and divide, it into inches and parts of an 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. i^i 

inch. From these pohits of division draw horizontal 
lines; from the point O draw the following lines and 
at the followinor angles from the horizontal line 
OP. 




Mnd View 



Side View 



Fig. 185. 



A line at 75° for polygons having 12 sides. 
72° " '' lo' " 

From the point O to the numerals denoting the 
radius of the polygon is the radius across the flats, 
while from point O to the horizontal line drawn from 




c 


A 


! 




C — 


- ~v 

e 


^ 7 


1 


^ 4^ 


I 


" 


11 

- + 


12 
/^ 8 

{ \ 


- 






) 





Fig. 186. 

those numerals is the radius across corners of the 
polygon. 



H- 



MECHANICAL DRAWING SELF-TAUGHT. 



A hexagon measures two inches across the flats: 
what is its diameter measured across the corners? 
Now from point O to the horizontal Hne marked j 
inch, measured, along the line of 60 degrees, is i 
5-32nds inches: hence the hexagon measures twice 



^ 



Fig. 187. . 

that, or 2 5-i6ths inches across corners. The proof 
of the construction is shown in the figure, the hex- 
agon and other polygons being marked simply for 
clearness of illustration. 



v^ 



Fig. 188. 



Let it be required to draw the stud shown in Fig- 
ure 185, and tlu' construction would be, for the pencil 
lines, as sliown in l^gure 1S6; line 1 is the centre h'nc, 



EXAMPLES IN BOLTS, NUTS, AND POLYGONS. 143 



arcs, 2 and 3 give the large, and arcs 4 and 5 the 
small diameter, to touch which lines 6, 7, 8, and 9 
may be drawn. Lines 10, 11, and 12 are then drawn 
for the leno-ths, and it remains to draw the curves in. 
In drawing these curves great exactitude is required 
to properly find their centres ; nothing looks worse in 
a drawine than an unfair or uneven junction between 
curves and straight lines. To find the location for 
these centres, set the compasses to the required radius 
for the curve, and from the point or corner A draw the 
arcs b and c, from c mark the arc e, and from b the 
arc d, and where d and e cross is the centre for the 
curve y^ 




Similarly for the curve h, set the compasses on i 
and mark the arc g, and from the point where It 
crosses line 6, draw the curve h. In inking in it is 
best to draw in all curves or arcs of circles first, and 
the straight lines that join them afterward, because. If 
the straight lines are drawn first, it- Is a difficult mat- 
ter to alter the centres of the curves to make them 



144 



MECHANICAL DRAWING SELF-TAUGHT. 



fall true, whereas, after the curves are drawn it is an 
easy matter, if it should be necessary, to vary the line 
a trifle, so as to make it join the curves correctly and 
fair. In inkinof in these curves also, care must be 




Fig. 190. 



taken not to draw them too short or too long-, as this 
would impair the appearance very much, as is shown 
in Figure 187. 




Fig. T91. 

To draw the piece shown in Figure 188, the lines 
are drawn in tlic order indicated by the letters in Fig- 
ure 189, the example being given for practice. It is 
well for the In^ginner to draw examples of common 
()l)jects, such as the liaml hammer in 1^'igure 190, or the 
chuck plate in Figure 191, which aftbrd good exam- 
ples in the th'awing of arcs and circles. 



IlXamples av bolts, nuts, axd polygons. 



145 



In Figure 191 i-z is a cap nut, and the order in which 
the same would be pencilled in Is Indicated by the re- 
spective numerals. The circles 3 and 4 represent the 
thread. 




Fig. 191 ^. 

In Figure 192 is shown the pencIlHng for a link 
having the hubs on one side only, so that a centre line 



146 MECHANICAL DRAWING SELF-TAUGHT. 

is unnecessary on the edge view, as all the lengths 
are derived from the top view, while the thickness of 
the stem and height of the hubs may be measured 
from the line A. In Figure 193 there are hubs (on 





Fig. 192. 

both sides of the link) of unequal height, hence a cen- 
tre line is necessary in both views, and from this line 
all measurements should be marked. 

In Figure 194 are represented the pencil lines for a 




Fig. 193. 

double eye or knuckle joint, as it is sometimes termed, 
an example that it is desirable for the student to draw 
in various sizes, as it is representative of a largc^ class 
of work. 



EXAMPLES EV BOLTS, NUTS, AND POLYGONS. i^y 

These eyes often have an offset, and an example of 
this is given in Figure 195, in which A is the centre 




Fig. 194. 

line for the stem distant from the centre line B of the 
eyes to the amount of offset required. 




Fig, 195. 

In Fiorure 196 is an example of a connecting rod 
end. From a point, as A, we draw arcs, as B C for 
the width, and E D for the length of the block, and 
throuo-h A we draw the centre line. It Is obvious, 
however, that we may draw the centre line first, and 



148 



MECHANICAL DRAWING SELF-TAUGHT. 



apply the measuring rule direct to the paper, and 
mark lines in place of the arcs B, C, D, E, and F, G, 
which are for the stem. As the block joins the stem 
in a straight line, the latter is evidently rectangular, 
as will be seen by referring to Figure 197, which rep- 



~^n^ 



^^^ 



-h 



- /I 



Fig. 196. 

resents a rod end with a round stem, the fact that the 
stem is round being clearly shown by the curves A B. 
The radius of these curves is obtained as follows: It 
is obvious that they will join the rod stem at the same 

F 



H -f 



r 



0- 



A- -l- 



0_ 



Fig. 197. 

point as the shoulder curves do, as denoted by the 
(knted vertical line. So likewise they join the curves 
l'^ F at th(! saiiK^ point in the rod length as the shoul- 
der curves, botli curves in fact beine formed bv the 

slioulder. The centre of the 



f^()!Mlcr <r 



EXAMPLES IN BO LIS, NUTS, AND POLYGONS. i^g 

radius of A or B must therefore be the same distance 
from the centre of the rod as is the centre from which 
the shoulder curve is struck, and at the same time at 
such a distance from the corner (as E or F) that the 
curve will meet the centre line of the rod at the same 
point in its length as the shoulder curves do. 

Figure 198 gives an example, in which the similar 




-V 



/ 



--W/7',. 



//J 



Fig. 198. 

curved lines show that a part is square. The figure 
represents a bolt with a square under the head. As 
but one view is given, that fact alone tells us that it 
must be round or square. Now we might mark a 
cross on the square part, to denote that it is square ; 
but this is unnecessary, because the curves F G show 
such to be the case. These curves are marked as 
follows: With the compasses set to the radius E, one 
point is rested at A, and arc B is drawn ; then one 
point of the compass is rested at C, and arc D is 
drawn ; giving the centre for the curve F by a similar 



ISO 



MECIIAXiCAL DRAWING SELF-TAUGHT. 



process on the other side of the figure, curve G Is 
drawn. Point C is obtained by drawing the dotted 
line across where the outHne curve meets the stem. 
Suppose that the corner where the round stem meets 
the square under the 'head was a sharp one instead of 
a curve, then the traditional cross w^ould require to be 
put on the square, as in Figure 199 ; or the cross will 





Fig. 200. 

be necessary if the corner be a round one, if the stem 
is reduced in diameter, as in Figure 200. 

Figure 201 represents a centre punch, giving an 




Fiu:. 201. 

example, in whicli the flat sides gradually run out 
upon a circle, thc^ edges forming curves, as at A, B, 
etc. The length of these curves is determined as fol- 



EXAMPLES IX BOLTS, XUTS, AXD POLYGOXS. 151 

lows : They must begin where the taper of the punch 
joins the parallel, or at C, C, and they must end on 
that part of the taper stem where the diameter is 
equal to the diameter across the flats of the octagon. 
All that is to be done then is to find the diameter 
across the flats on the end view^ and mark it on the 
taper stem, as at D, D, which will show where the 
flats terminate on the taper stem. And the curved 
lines, as A, B, may be drawn in by a curve that must 
meet at the line C, and also in a rounded point at 
line D. 



CHAPTER VIII. 

SCREW THREADS AND SPIRALS. 

The screw thread for small bolts is represented by 
thick and thin lines, such as was shown in Figure 152, 
but in larger sizes; the angles of the thread also are 
drawn in, as in Figure 202, and the method of doing 
this is shown in Figure 203. The centre line i and 
lines 2 and 3 for the full diameter of the thread being- 




drawn, set the compasses to tlie required pitch of the 
tliread, and stepping ah^ig line 2, mark the arcs 4, 
5, 6, etc., for the full length the thread is to be 
marked. W'iih the triangle resting against the X- 
s(|uare, the lines 7, S, 9, etc. (for die full length of the 
thrcMcl), arc ch-awn from the points 4, 5, 6, on line 2. 
Tlu.'se give one side of the tliread. Reversing the 
(h-aVvinir trianLile 



angles 10, 11, etc., are then 



(>52) 



SCREW THREADS AND SPIRALS. j-^ 

drawn, which will complete the outline of the thread 
at the top of the bolt. We may now mark the dtipth 
of the thread by drawing line 12, and with the com- 




passes set on the centre line transfer this depth to the 
other side of the bolt, as denoted by the arcs 13 and 
14. Touching- arc 14 we mark line 15 for the thread 



154 



MECHANICAL DRAWING SELF-TAUGHT. 



depth on that side. We have now to get the slant of 
the thread across the bolt. It is obvious that in 
passing once around the bolt the thread advances to 
the amount of the pitch as from a to b ; hence, in 
passing half way aro»und, it will advance from a to c; 
we therefore draw line 1 6 at a right-angle to the cen- 
tre line, and a line that touches the top of the threads 
2X a, where it meets line 2, and also meets line 16, 
where it touches line 3, is the angle or slope for the 
tops of the threads, which may be drawn across by 
lines, as 18, 19, 20, etc. From these lines the sides of 
the thread may be drawn at the bottom of the bolt, 
marking first the angle on one side, as by lines 21, 22, 

23, etc., and then the angles on the other, as by lines 

24, 25, etc. 




Fig. 204. 

There now remain the bottoms of thfe thread to 
draw, and this is done by drawing lines from the bot- 
tom of the thread on one side of the bolt to the bot- 
tom on the other, as shown in the cut by a dotted line; 
hence, we may set a square blade to that angle, and 
mark in these lines, as 26, 27, 28, etc., and the thread 
is pc^ncilled in com])U;te. 

If the stiidcni will follow out this example upon 



SCREW THREADS AND SPIRALS. 



155 



paper, It will appear to him that after the thread had 
been marked out on one side of the bolt, the angle of 
the thread might be obtained, as shown bylines 16 
and 17, and that the bottoms of the thread as well as 
the tops might be carried across the bolt to the other 




side. Figure 204 represents a case in which this has 
been done, and it will be observed that the lines de- 
noting the bottom of the thread do not meet the bot- 
toms of the thread, which occurs for the reason that the 




angle for the bottom is not the same as that for the 
top of the thread. 

In Inking in the thread. It enhances the appearance 
to give the bottom of the thread and the right-hand 



156 



MECHANICAL DRAV/ING SELF-TAUGHT. 



side of the same, heavy shade lines, as in Figure 202, 
a plan that is usually adopted for threads of large di- 
ameter and coarse pitch. 

A double thread, such as in Figure 205, is drawn in 
the same way, except ' that the slant of the thread is 
doubled, and the square is to be set for the thread- 
pitch A, A, both for the tops and bottoms of the 
thread. 

A round top and bottom thread, as the Whitworth 




Fig. 207. 

thread, is drawn by single lines, as in Figure 206. 
A left-hand thread, Figure 207, is obviously drawn by 
the same process as a right-hand one, except that the 
slant of the thread is given in the opposite direction. 

For screw threads of a large diameter it is not un- 
common to draw in the thread curves as they appear 
to the eye, and the method of doing this is shown in 
iMgure 208. The thread is first marked on both sides 
of the boil, as explained, and instead of drawing, 
straight across the bolt, lines to represent tlie tops 
and bottoms of the thread, a template to draw tht^ 
curves by is requiriMl, To get these curves, two half- 
circles, one equal in dlanieter to the top, and oni' 






SCKEJy THREADS AND SPIRALS. 



:>/ 



equal to the bottom of the thread, are drawn, as in 
Figure 208. 

These half-circles are divided Into any convenient 
number of equal divisions: thus in Figure 208, each has 
eight divisions, as a, b, c, etc., for the outer, and ^, /, k, 
etc., for the inner one. The pitch of the thread is 



Fitch 




Fig. 208. 

then divided off by vertical lines Into as many equal 
divisions as the half-circles are divided Into, as by 
the lines a, d, c, etc., to 0. Of these, the seven from a, 
to //, correspond to the seven from a' to g\ and are 
for the top of the thread, and the seven from i to o 
correspond to the seven on the inner half-circle, as /, 
y, k, etc. Horizontal lines are then drawn from the 



I eg MECHANICAL DRAWING SELF-TAUGHT. 

points of the division to meet the vertical Hnes of di- 
vision; thus the horizontal dotted line from a' meets 
the vertical line a, and where they meet, as at A, a dot 
is made. Where the dotted line from b' meets verti- 
cal line b, another dot is made, as at B, and so on 
until the point G is found. A curve drawn to pass 
from the top of the thread on one side of the bolt to 
the top of the other side, and passing through these 
points, as from A to G, will be the curve for the top 
of the thread, and from this curve a template may be 
made to mark all the other thread-tops from, because 
manifestly all the tops of the thread on the bolt will 
be alike. 

For the bottoms of the thread, lines are similarly 
drawn, as from i' to meet i, where dot I is marked. J is 
got from/' andy, while K is got from the intersection of 
k' with k, and so on, the dots from I to O being those 
through which a curve is drawn for the bottom of the 
thread, and from this curve a template also may be 
made to mark all the thread bottoms. We have In 
our example used eight points of division in each 
half-circle, but either more or less points maybe used, 
tlie only requisite being that the pitch of the thread 
must be divided into as many divisions as the two half- 
circles ar \ But it Is not absolutely necessary that 
both lialt-circles be divided Into the same number of 
(!qual divisions. Thus, suppose the large half-circle 
were divided into ten divisions, then instead of the first 
half of the ])it(:h being divided into eight (as from a 
lo h) It would require to have ten lines. But tlu^ 
iniur half-circle may have eight only, as in our ex- 
cimplc!. It is more ronvcnicnf. lunvrvcr to u-;c the 



SCREW THREADS AND SPIRALS. j^q 

same number of divisions for both circles, so that 
they may both be divided together by Hnes radiating 
from the centre. The more the points of division, the 
greater number of points to draw the curves through; 
hence it is desirable to have as many as possible, 
which is governed by the pitch of the thread, it being 
obvious that the finer the pitch the less the number of 
distinct and clear divisions it Is practicable to divide 
it Into. In our example the angles of the thread are 
spread out to cause these lines to be thrown further 
apart than they would be in a bolt of that diameter; 
hence It will be seen that In threads of but two or 
three Inches in diameter the lines w^ould fall very 
close together, and would require to be drawn finely 
and with care to keep them distinct. 

The curves for a United States standard form of 
thread are obtained in the same manner as from the 
V thread in Figure 208, but the thread itself Is more 
difficult to draw. The construction of this thread Is 
shown In Figure 208, it having a flat place at the top 
and at the bottom of the thread. A common V thread 
has Its sides at an angle of 60 degrees, one to the 
other, the top and bottom meeting In a point. The 
United States standard is obtained from drawing a 
common V thread and dividing Its depth into eight 
equal divisions, as at x, in Figure 208 a, and cutting 
off one of these divisions at the top and filling In one 
at the bottom to form flat places, as shown In the figure. 
But the thread cannot be sketched on a bolt by this 
means unless temporary lines are used to get the 
thread from, these temporary lines being drawn to 
represent a bolt one-fourth the depth of the thread too 



l60 MECHANICAL DRAWING SELF-TAUGHT, 

large In diameter. Thus, in Figure 208 a, it is seen 
that cutting off one-eighth the depth of the thread re- 
duces the diameter of the thread. It is necessary, 
then, to draw the fiat place on top of the thread first, 




Fig. 208 (T. 



the order of procedure being shown in Figure 209. 
The Hnes for the full diameter of the thread being 




Fiti'. 209. 

drawn, the plu.li is stepped off by arcs, as i, 2,3, etr.; 
and from these, arcs, as 4, 5, 6, etc., arc marked for 
the widlli of ih'' Hnt mI uv-s at the tops of tlie threads. 



SCREW THREADS AND SPIRALS. j^j 

Then one side of the thread Is marked off by lines, as 
7, which meet the arcs i, 2, 3, etc., as at a^ c, etc. 
Similar lines, as 8 and 9, are marked for the other 
side of the thread, these lines, 7, 8 and 9, projecting 
until they cross each other. Line 10 is then drawn, 
making a flat place at the bottom of the thread equal 
in width to that at the top. Line 12 is then drawn 
square across the bolt, starting from the bottom of the 
thread, and line 13 is drawn starting from the corner 
/on one side of the thread and meeting line 12 on 
the other side of the thread, which gives the angle for 
the tops of the thread. The depth of the thread may 
then be marked on the other side of the bolt by the 
arcs d and e, and the line 14. The tops of all the 
threads may then be drawn in, as by lines 15, 16, 17 
and 18, and by lines, as 19, etc., the thread sides may 
be drawn on the other side of the bolt. All that re- 
mains is to join the bottoms of the threads by lines 
across the bolt, and the pencil lines will be complete, 
ready to ink in. If the thread is to be shown curved 
Instead of drawn straight across, the curve may be 
obtained by the construction in Figure 208, which is 
similar to that In Figure 207, except that while the 
pitch is divided off into 1 6 divisions, the whole of these 
16 divisions are not used to get the curves, some of 
them beincr used twice over; thus for the bottom the 
eight divisions from b to /are used, while for the tops 
the eight from g "^o are used. Hence g, h and i are 
used for o-ettinor both curves, the divisions from a X.o b 
and from to p being taken up by the flat top and 
bottom of the thread. It will be noted that In Figure 
207, the top of the thread is drawn first, while In Fig- 



l62 



MECHANICAL DRAWING SELF-TAUGHT. 



Lire 208 the bottom is drawn first, and that In the 
latter (for the U. S. standard) the pitch is marked 
from centre to centre of the flats of the thread. 

To draw a square thread the pencil lines are marked 
in the order shown in Figure 210, in which i repre- 




sents the centre line and 2, 3, 4 and 5, the diameter 
and depth of the thread. The pitch of the thread is 
marked off by arcs, as 6, 7, etc., or by laying- a rule di- 
rectly on the centre line and marking with a lead pen- 
cil. To obtain the slant of the thread, lines 8 and 9 
are drawn, and from these line 10, touching 8 and 9 
where they meet lines 2 and 5 ; the threads iiui)' then 
be drawn in from the arcs as 6, 7, etc. The side of 
the thread will show at the top and the bottom as at 
A B, because of the coarse pitch and the thread on 
the other or unseen side of the bolt slants, as denoted 
by the Units 12, 13 ; and hence to draw the sides A B, 
the triangles must be set from one thread to the next 
on the opposite side of the bolt, as denoted b)' the 
dotted lines 12 and i 3. 

Jf the curves of the thread are to be drawn in. they 



SCR E IV THREADS AND SPIRALS. 163 

may be obtained as in Figure 211, which is substan- 
tially the same as described for a V thread. The 
curves^ representino- the sides of the thread, termi- 




nate at the centre line^, and the curves e are equi- 
distant with the curves c from the vertical lines d. As 



:64 



MECHANICAL DRAWING SELF-TAUGHT. 



the curves f above the Hne are the same as f below 
the line, the template for f need not be made to ex- 
tend the whole distance across, but one-half only; as 




is sliown by the dotted curve ^«,'-, in the construction for 
finding the curve for square-threaded nuts in Fio-ure 

2 I 2. 



SCREJV THREADS AND SPIRALS. i5t 

A Specimen of the form of template for drawing 
these curves Is shown In Figure 213 ; g g, Is the cen- 
tre Hne parallel to the edges R, S ; lines m, n, repre- 
sent the diameter of the thread at the top, and 0, p, 
that at the bottom or root ; edge a Is formed to the 
points (found by the construcdons in the figures as 
already explained) for the tops of the thread, and edge 
/ Is so formed for the curve at the thread bottoms. 
The edge, as S or R, is laid against the square-blade 




Fig. 213. 

to steady it while drawing In the curves. It may be 
noted, however, that since the curve Is the same below 
the centre line as It is above, the template may be made 
to serve for one-half the thread diameter, as at^ where 
it Is made from to g, only being turned upside down 
to draw the other half of the curve ; the notches cut 
out at X, X, are merely to let the pencil-lines in the 
drawing show plainly when setting the template. 



1 56 MECHANICAL DRAWING SELF-TAUGHT. 

When the thread of a nut is shown in section, it 
slants in the opposite direction to that which appears 
on the bolt-thread, because it shows the thread that 
fits to the opposite side of the bolt, which, therefore, 
slants in the opposite direction, as shown by the lines 
12 and 13 in Figure 210. 

In a top 6r end view of a nut the thread depth is 
usually shown by a simple circle, as in Figure 214. 




Fig. 214. 

To draw a spiral spring, draw the centre line A, and 
lines B, C, Figure 215, distant apart the diameter 
the spring is to be less the diameter of the wire of 
which it is to be made. On the centre line A mark 
two lines a b, c d, representing the pitch of the spring. 
Divide the distance between a and b into four equal di- 
visions, as by lines i, 2, 3, letting line 3 meet line B. 
Line e meeting the centre line at line a, and the line 
B at its intersection with line 3, is the angle of the 
coil on one side of the spring ; hence it may be marked 
in at all the locations, as at cf, etc. These lines give 
at their intersections with the lines C and B the cen- 
tres for the half circles g, which being drawn, the sides 
//, /,y, /v, c!tc., of tlie spring, may all be marked in. By 
the lines ;;/, 7/, o, /, the other si(l(\s of the spring may 
be marked in. 



SCJ^EIV THREADS AND SP/A\1/.S. i^y 

The end of the spring Is usually marked straight 
across, as at L. If It Is required to draw the coils 
curved instead of straight across, a template must be 
made, the curve being obtained as already described 




Fig. 215. 

for threads. It may be pointed out, however, that to 
obtain as accurate a division as possible of the lines 
that divide the pitch, the pitch may be divided upon 



mm 



1 68 MECHANICAL DRAWING SELF-TAUGHT. 

a diagonal line, as F, Figure 216, which will greatly 
facilitate the operation. 




Fig. 216. 

Before going into projections It may be as well to 
give some examples for practice. 




-10" — 
Section tliroiKjh A. B. 



Fii;. 219. 



Hole for Set-Screw 'yl^ Tapped U Threads 



Front Elevation of 
Rod, without Brass. 



P / 



r 



j^AC.O. 



will be cast from the same patterns . 

SCALE OF INCHES. 



3 3 4 S . S 




'ge 169.) 



( 



Bax:k Elevation of Brass 



i 



li. 



CHAPTER IX. 

EXAMPLES EOR PRACTICE. 

Figure 217 represents a simple example for prac- 
tice, which the student may draw the size of the en- 
graving, or he may draw it twice the size. It is a 




Fig. 217. 

locomotive spring, composed of leaves or plates, held 
together bv a central band. 

Figure 218 is an example of a stuffing box and 
gland, supposed to stand vertical, hence the gland has 
an oil cup or receptacle. 

In Figure 219 are working drawings of a coupling 
rod, with the dimensions and directions marked in. 

It may be remarked, however, that the drawings of 
a workshop are, where large quantities of the same 
kind of work is done, varied in character to suit some 
special departments — that is to say, special extra draw- 
ings are made for these departments. In Figures 
220 and 221 is a drawing of a coimecting rod drawn, 
put together as it would be for the lathe, vise or erect- 
ing shop. 

^169) 



170 



MECHANICAL DRAWING SELF-TAUGHT. 




Fig, 218. 




v^— i^iiyiiyr Fig. 220. 



c^ 



^ ^ UJJ ^ 






Fig. 221. 



I 



^^ 



EXAMPLES FOR PRACTICE. 171 

To the two views shown there would be necessary 
detail sketches of the set screws, gibbs, and keys, all 
the rest being shown ; the necessary dimensions being, 
of course, marked on the general drawing and on the 
details. 

In so simple a thing as a connecting rod, however, 
there would be no question as to how the parts go 
together; hence detail drawings of each separate piece 
would answer for the lathe or vise bands. 

But in many cases this would not be the case, and 
the drawing would require to show the parts put to- 
gether, and be accompanied with such detail sketches 
as might be necessary to show parts that could not be 
clearly defined in the general views. 

The blacksmith, for example, is only concerned 
with the making of the separate pieces, and has no 
concern as to how the parts go together. Further- 
more, there are parts and dimensions In the general 
drawing with which the blacksmith has nothing to do. 

Thus the location and dimensions of the keyw^ays, 
the dimensions of the brasses, and the location of the 
bolt holes, are matters that have no reference to the 
blacksmith's work, because the keyways, bolt holes, 
and set-screw holes would be cut out of the solid In 
the machine shop. It Is customary, therefore, to send 
to the blacksmith shop drawings containing separate 
views of each piece drawn to the shape it is to be 
forged ; and drawn full size, or else on a scale suffi- 
ciently large to make each part show clearly without 
close Inspection, marking thereon the full sizes, and 
stating beneath the number of pieces of each detail. 
(As In Figure 222, which represents the Iron work of 



1/2 



MECHANICAL DRAWING SELF-TAUGHT. 



r— J 



ONE THUS, 



lJ 




ONE THUS. 



n 



Vb 



1 



i 



ONE THUS. 



o 



three thits. 
(cast steel.) 



TWO Tlins, IWO THUS. 
Fig. 2 22 



ONE THUS. 



EXAMPLES FOR PRACTICE. j-.^ 

the connecting rod in Figure 220). In some cases 
the finished sizes are marked, and it is left to the 
blacksmith's judgment how much to leave for the fin- 
ishing. This is undesirable, because either the black- 
smith is left to judge what parts are to be finished, or 
else there must be on the drawing instructions on this 
point, or else signs or symbols that are understood to 
convey the information. It is better, therefore, to 
make for the blacksmith a special sketch, and mark 
thereon the full-forored sizes, statinor on the drawinof 
that such is the case. 

As to the material of which the pieces are to be 
made, the greater part of blacksmith work is made of • 
wrought iron, and it is, therefore, unnecessary to write 
"wrought iron" beneath each piece. When the pieces 
are to be of steel, however, it should be marked on 
the drawing and beneath the piece. In special cases, 
as where the greater part of the work of the shop is 
of steel, the rule may, of course, be reversed, and the 
parts made of iron may be the ones marked, whereas 
when parts are sometimes of iron, and at others of 
steel, each piece should be marked. 

As a general rule the blacksmith knows, from the 
custom of the shop or the nature of the work, what 
the quality or kind of iron is to be, and it is, therefore, 
only in exceptional cases that they need to be men- 
tioned on the drawing. Thus in a carriage manufac- 
tory, Norway or Swede iron will be found, as well as 
the better grades of refined iron, but the blacksmith 
will know what iron to use, for certain parts, or the 
shop may be so regulated that the selection of the 
iron is not left to him. In marking the number of 



X 



J ^4 MECHANICAL DRAWING SELF-TAUGHT. 

pieces required, it is better to use the word " thus " 
than the words "of this," or "off this," because it is 
shorter and more correct, for the forging is not taken 
off the drawing, nor is it of the same ; the drawing 
gives the shape an'd the size, and the word " thus " 
conveys that idea better than "of," "off," or "like 
this." 

In shops where there are many of the same pieces 
forged, the blacksmith is furnished with sheet-iron 
templates that he can lay directly upon the forging 
and test its dimensions at once, which is an excellent 
plan in large work. Such templates are, of course, 
made from the drawings, and it becomes a question 
as to whether their dimensions should be the forored 
or the finished ones. If they are the forged, they may 
cause trouble, because a forging may have a scant 
place that it is difficult for the blacksmith to bring up 
to the size of the template, and he is in doubt whether 
there is enough metal in the scant place to allow the 
job to clean up. It is better, therefore, to make them 
to finished sizes, so that he can see at once if the work 
will clean up, notwithstanding the scant place. This 
will lead to no errors in large work, because such 
work is marked out by lines, and the scant part will 
therefore be discovered by the machinist, who will 
line out the piece accordingly. 

Figure 223 is a arawi ng of a locomotive frame, 
which the student may as well draw three or four 
times as large as the engraving, which brings us to 
the subject of enlarging or reducino- scales. 



EXAMPLES FOR PRACTICE. 



i;5 



REDUCING SCALES. 

It is sometimes necessary to reduce a drawing to a 




smaller scale, or to find a minute fraction of a given 



1^6 MECHANICAL DRAWING SELF-TAUGHT. 

dimension, such fraction not being marked on the 
lineal measuring rules at hand. Figure 224 repre- 
sents a scale for finding minute fractions. Draw 
seven lines parallel to each other, and equidistant 
draw vertical lines dividing the scale into half-inches, 



, R rl. c b a 


5 A 7 








4/\% 








3/ \o 








2 / \lO 








1/ \1 








/ \| 







Fig. 224. 

as at a, b, c, etc. Divide the first space e d into 
equal halves, draw diagonal lines, and number them 
as in the figure. The distance of point i, which is at 
the intersection of diaoronal with the second horizontal 



c 


) 


[ 


2 S 




5 ( 






i 


K 























1 


















I 


1 








8 

7 




1 




1 


\ 


1 


I 




1 


1 






1 


1 


\ 


\ 




1 


1 


1 




1 




1 






\ 


I 


I 




1 




1 


5 

4 
3 








\ 










1 




1 








\ 


I 








1 




1 




1 






i 


1 


















\ 










1 






f 












1 


1 






1 


( 




A 




z 


) 




t 


J 


r 


c 1 


i 




^ 



Fig. 225. 

line, will be J^ incli from vertical line c\ Point 2 will 
be "liV inch from line 6', and so on. Vov tenths of inches 
there would rcciulrc! to be but six horizontal lines, the 
diagonals bciiii' drawn as l)erore. A similar scale is 
shown In iMgurc 225. Draw the lines A B, B D. D C, 



EXAMPLES FOR PRACTICE. I -7 

C A, enclosing a square Inch. Divide eacli of these lines 

into ten equal divisions, and number and letter them as 

shown. Draw also the diagonal lines A i, <^ 2, B 3, 

and so on ; then the distances from the line A C to 

the points of intersection of the diagonals with the 

horizontal lines represent hundredths of an Inch. 

Suppose, for example, we trace one diagonal line In 

its path across the figure, taking that which starts from 

A and ends at i on the top horizontal line ; then where 

the diagonal intersects Jwrizoiital line i,is ^ from 

the line B D, and ,^ from the line A C, while where It 

intersects horizontal line 2, is J^ from line B D, and 

,^3 from line A C, and so on. If we require to set the 

compasses to ^l^ Inch, we set them to the radius of n, 

and the figure 3 on line B D, because from that 3 to 

the vertical line ^ 4 is f^ or f^ inch, and from that 

vertical line to the dlac^onal at n is seven divisions 

from the line C D of the figure. 

In maklnor a drawing to scale, however, It Is an ex- 
00'' 

cellent plan to draw a line and divide It off to suit the 
required scale. Suppose, for example, that the given 
scale is one-quarter, size, or three inches per foot; then 
a line three Inches long may be divided Into twelve 
equal divisions, representing twelve inches, and these 
may be subdivided into half or quarter inches and so 
on. It is recommended to the beginner, however, to 
spend all his time making simple drawings, without 
makinor them to scale, in order to become so fam'lllar 
with the use of the instruments as to feel at home 
with them, avoiding the complication of early studies 
that would accompany drawing to scale. 



1% 



CHAPTER X. 
PROJECTIONS. 

In projecting, the lines in one view are used to 
rtiark those in other views, and to find their shapes or 
curvature as they will appear in other views. Thus, 
in Figure 225^ we have a spiral, wound around a cyl- 
inder whose end is cut off at an angle. The pitch of 
the spiral is the distance A B, and we may delineate 
the curve of the spiral looking at the cylinder from 
two positions (one at a right-angle to the other, as Is 
shown in the figure), by means of a circle having a 
circumference equal to that of the cylinder. 

The circumference of this circle we divide into any 
number of equidistant divisions, as from i to 24. 
The pitch A B of the spiral or thread is then divided 
off also into 24 equidistant divisions, as marked on 
the left hand of the figure; vertical lines are then 
drawn from the points of division on the circle to the 
points correspondingly numbered on the lines dividing 
the pitch; and where line i on the circle intersects 
line I on the pitch is one point in the curve. Sim- 
ilarly, where point 2 on the circle intersects line 2 on 
the pitch is another point in the curve, and so on for 
the whole 24 divisions on the circle and on the pitch. 
In this view, however, the path of the spiral from line 
7 to line 19 lies on the other side of the cylinder, and 
is marked in dotted lines, because it is hidden by the 



PROJECTIONS. 



79 



cylinder. In the right-hand view, however, a different 




portion of the spiral or thread is hidden, namely from 



I go MECHANICAL DRAWING SELF- TAUGHT, 

lines I to 13 Inclusive, being an equal proportion to 
that hidden in the left-hand view. 

The top of the cylinder Is shown In the left-hand 
view to be cut off at an angle to the axis, and will 
therefore appear elliptical ; in the right-hand view, to 
delineate this oval, the same vertical lines from the 
circle may be carried up as shown on the right hand, 
and horizontal lines may be drawn from the inclined 
face in one view across the end of the other view, as 
at P; the divisions on the circle may be carried up on 
the right-hand vlew^ by means of straight lines, as Q, 
and arcs of circle, as at R, and vertical lines drawn 
from these arcs, as line S, and where these vertical 
lines S intersect the horizontal lines as P, are points 
in the ellipse. 

Let it be required to draw a cylindrical body join- 
ing another at a right-angle; as for example, a Tee, 
such as in Figure 226, and the outline can all be 
shown in one view, but it is required to find the line 
of junction of one piece, A, with the other, B ; that is, 
find or mark the lines of junction C. Now when the 
diameters of A and B are equal, the/ line of junction C 
is a straight line, but it becomes a curved one when 
the diameter of A Is less than that of B, or z'ice versa; 
hence it may be as well to project it in both cases. 
For this purpose the three views arc necessary. One- 
quarter of the circle of B, in the end view, is divided 
off Into any number of equal divisions ; thus we have 
cliosen tlic divisions marked a, h, r, ^/, e, etc. ; a 
(piarter of llic^ top view is similarly divided off, as at 
/ 0^, //, /, j : from these points of division lines arc 
projected on to the side view, as shown by the dotted 



PROJECTIONS. 



I8l 



lines k, /, m, n, o, /, etc., and where these lines meet, 
as denoted by the dots, is in each case a point In the 
line of junction of the two cylinders A, B. 



End Tlevo 




Side View j^^jp View 

Fig- 226. 

Figure 227 represents a Tee, in which B is less in 
diameter than A; hence the two join in a curve, which 
is found in a similar manner, as is shown in Figure 



I82 



MECHANICAL DRAWING SELF-TAUGHT. 



227. Suppose that the end and top views are drawn, 
and that the side view is drawn in outline, but that 
the curve of junction or intersection is to be found. 




Toi) View 



Fig. 227. 



Now it is evident diat since the centre line i passes 
ihroun-h the side and end views, that die face a, in the 



k 



PROJECTIONS. I S3 

end view, will be even with the face <x in the side view, 
both beine the same face, and as the full lencrth of the 
side of B in the end view is marked by line b, there- 
fore line c projected down from b will at its junction 
with line b\ which corresponds to line b, give the ex- 
treme depth to which b' extends into the body A, and 
therefore, the apex of the curve of intersection of B 
w^ith A. To obtain other points, we divide one-quarter 
of the circumference of the circle B in the top view 
into four equal divisions, as by lines d, e,f] and from 
the points of division we draw lines/, /, g, to the centre 
line marked 2, these lines being thickened in the cut 
for clearness of illustration. The compasses are 
then set to the length of thickened line g^ and from 
point //, in the end view, as a centre, the arc g' is 
marked. With the compasses set to the length of 
thickened line i, and from h as a centre, arc i' is 
marked, and with the length of thickened line / as a 
radius and from // as a centre arc/' is marked; from 
these arcs lines k, /, m are drawn, and from the intersec- 
tion of k, /, m, with the circle of A, lines ;/, o, p are let 
fall. From the lines of division, d, e,f, the lines q, r, s 
are drawn, and where lines 71, 0, p join lines q, r, s, are 
points in the curve, as shown by the dots, and by 
drawino^ a line to intersect these dots the curve is 
obtained on one-half of B. Since the axis of B is in 
the sam.e plane as that of A, the lower half of the 
curve is of the same curvature as the upper, as is 
shown by the dotted curve. 

In Figure 228 the axis of piece B is not in the same 
plane as that of D, but to one side of it to the dis- 
tance between the centre lines C, D, which is most 



L 



1 84 



MECHANICAL DRAWING SELF-TAUGHT. 



clearly seen in the top view. In this case the process 
is the same except in the following points : In the 
side view the line w, corresponding to the line w in the 

'End View 




end view, passes witliin the line .r before the curve of 
intersection begins, and in transferrino- die lengths of 



PROJECTIONS. 



185 



the full lines b, c, d, e, f, to the end view, and mark- 
ing the arcs b\ d, d\ d, fi they are marked from the 
point w (the point where the centre line of B inter- 
sects the oudine of A), instead of from the point x. 
In all other respects the construction is the same as 
that in Figure 227. 



lEnd View 




Side [View 



Fig. 229. 



In these examples the axis of B stands at a right- 
angle to that of A. But in Figure 229 is shown the 
construction where the axis of B is not at a rieht- 



1 86 MECHANICAL DRAWING SELF-TAUGHT. 

angle to A. In this case there is projected from B, in 
the side view, an end view of B as at B i, and across 
this end at a rio^ht-ano^le to the centre line of B is 
marked a centre line C C of B', which is divided 
as before by lines d, e, f, g, h, their respective 
lengths beinof transferred from W as a centre, and 
marked by the arcs d\ e! /,' which are marked on a 
vertical line and carried by horizontal lines, to the arc 
of A as at i, j\ k. From these points, i, j\ k, the perpen- 
dicular lines /, m, n, o, are dropped, and where these lines 
meet lines/, q, r, s, t, are points in the curve of inter- 
section of B with A. It will be observed that each of 
the lines m, n, o, serves for two of the points in the 
curve ; thus, m meets q and s, while n meets/ and /, and 
meets the outline on each side of B, in the side view, 
and as /, j, k are obtained from d and e, the lines 
g and h might have been omitted, being inserted 
merely for the sake of illustration. 

In Figure 230 is an example in which a c^dinder in- 
tersects a cone, the axes being parallel. To obtain 
the curve of intersection in this case, the side view is 
divided by any convenient number of lines, as a, b, r, 
etc., drawn at a right-angle to its axis A A, and from 
one end of these lines are let fall the perpendiculars 
f^ g^ K hj '> from the ends of these (where they meet 
the centre line of A in the top view), half-circles k, /, ;;/, 
11, o, are drawn to meet the circle of B in the top view, 
and from their points of intersection with B, lines /, 
q, r, s, t, arc drawn, and where these meet lines a, b, c, 
d and e, whicli is at 7C, v, w, x, y, are points in the curve. 

It will be observed, on referring again to Figure 229, 
lliat the branch or cylinder B appears to be of ellipti- 



PROJECTIONS. 



1 87 



cal section on its end face, which occurs because it is 
seen at an angle to its end surface ; now the method 



Side View 




Top View 

Fig. 230. 



of finding the ellipse fof any given degree of angle is 



1 38 MECHANICAL DRAWING SELF-TAUGHT. 

as in Figure 231, in which B represents a cylindrical 
body whose top face would, if viewed from point I, ap- 
pear as a straight line, while if viewed from point J it 
would appear in outline a circle. Now if viewed from 
point E its apparent dimension in one direction will 
obviously be defined by the lines S, Z. So that if on a 
line G G at a right angle to the line of vision E, we 
mark points touching lines S, Z, we get points i and 2, 
representing the apparent dimension In that direction 



w 



-^<\^ 



J^ 






\C^ 



Fig. 231. 

which is the width of the ellipse. The length of the 
ellipse will obviously be the full diameter of the cyl- 
inder B ; hence from E as a centre we mark points 3 
and 4, and of the remaining points we will speak 
presently. Suppose now the angle the top face of B 
is viewed from Is denoted by the line L, and lines S', Z, 
parallel to L, will be the width for the ellipse whose 
lengdi Is marked by dots, equidistant on each side 
of centre line Ci' G', which equal In their widths one 



PR OJECTIONS. I 3q 

from the other the full diameter of B. In this con- 
struction the elHpse will be drawn away from the cyl- 
inder B, and the ellipse, after being found, would have 
to be transferred to the end of B. But since centre 
line G G is obviously at the same angle to A A that 
A A Is to G G, we may start from the centre line of 
the body whose elliptical appearance is to be drawn, 
and draw a centre line A A at the same angle to G G 
as the end of B is supposed to be viewed from. This 
is done in Figure 231 ^, in which the end face of B is 
to be drawn viewed from a point on the line G G, but 
at an angle of 45 degrees; hence line A A Is drawn 
at an angle of 45 degrees to centre line G G, and 
centre line E is drawn from the centre of the end of B 
at a right angle to G G, and from where it cuts A A, as 
at F, a side view of B is drawn, or a single line of a 
length equal to the diameter of B may be drawn at a 
right angle to A A and equidistant on each side of F. 
A line, D D, at a right angle to A A, and at any conve- 
nient distance above F, is then drawn, and from its in- 
tersection with A A as a centre, a circle C equal to the 
diameter of B is drawn; one-half of the circumference 
of C is divided off into any number of equal divi- 
sions as by arcs a, b, c, d, e, f. From these points of 
division, lines g, h, i, j, k, I are drawn, and also lines 
m, n, 0, p, q, r. From the Intersection of these last 
lines with the face in the side view, lines s, t, ti, v, w, x, 
J/, z are drawn, and from point F line E is drawn. Now 
it is clear that the width of the end face of the cylinder 
will appear the same from any point of view it may be 
looked at, hence the sides H H are made to equal the 
diameter of the cylinder B and marked up to centre 
line E. 



1 90 



MECHANICAL DRAWING SELF-TAUGHT. 



It is obvious also that the Hnes s^ z, drawn from the 
extremes of the face to be projected will define the 




Fig. 231 rZ. 
width of tlic ellipse, hence we have four of the points 
(marked respecllvely i, 2, 3, 4) in the elHpse. lo ob- 



PROJECTIONS. igi 

tain the remaining points, lines /, u, v, zu, x, y (which 
start from the point on the face F where the Hnes w, 
7/, 0, p, q. r, respectively meet it) are drawn across the 
face of B as shown. The compasses are then set to 
the radius o-; that is, from centre line D to division a 
on the circle, and this radius is transferred to the face 
to be projected the compass-point being rested at the 




']g. 232 



intersection of centre line G and line /, and two arcs 
as 5 and 6 drawn, giving two more points in the curve 
of the ellipse. The compasses are then set to the 
length of line h (that is, from centre line D to point 
of division ^), and this distance is transferred, setting 
the compasses on centre line G where it is intersected 



ft 



IQ2 MECHANICAL DRAWING SELF-TAUGHT. 

by line tt, and arcs 7, 8 are marked, giving two more 
points in the ellipse. In like manner points 9 and 10 
are obtained from the length of line /, 1 1 and 1 2 from 
that of /; points 13 and 14 from the length oik, and 
1 5 and 16 from /, and the ellipse may be drawn in from 
these points. 

It may be pointed out, however, that since points 5 
and 6 are the same distance from G that points 15 
and 16 are, and since points 7 and 8 are the same 
distance from G that points 13 and 14 are, while 
points 9 and 10 are the same distance from G that 11 
and 12 are, the lines/, kJ are unnecessary, since / and 
g are of. equal length, as are also h and /^ and /and/. 
In Figure 232 the cylinders are line shaded to make 
them show plainer to the eye, and but three lines (a, 
b, c) are used to get the radius wherefrom to mark 
the arcs where the points In the ellipse shall fall; thus, 
radius a gives points i, 2, 3 and 4; radius b gives 
points 5, 6, 7 and 8, and radius c gives 9, 10, 11 and 
I 2, the extreme diameter being obtained from lines S, 
Z, and H, H. 



CHAPTER XI. 
DRAWING GEAR WHEELS. 

The names given to the various lines of a tooth on 
a gearwheel are as follows: 

In Figure 233, A Is the face and B the flank of a 
too.th, while C is the point, and D the root of the; 




tooth; E is the height or depth, and F the breadth. 
P P is the pitch circle, and the space between the two 
teeth, as H, is termed a space. 

It is obvious that the points of the teeth and the 
13 (193) 



194 



MECHANICAL DRAWING SELF-TAUGHT. 



bottoms of the spaces, as well as the pitch circle, are 
concentric to the axis of the wheel bore. x\nd to 
pencil in the teeth these circles must be fully drawn, 




as in Figure 234, in which l^ P is the pitch circle. 
This circle is divided into jis many equal divisions as 



DI^AIVIXG GEAR WHEELS. 



195 



IS 



I7>' 



to have teeth, these divisions belnof 
the radial Hnes, A, B, C, etc. Where 



-e whc 
denoted 

these di\'isions intersect the pitch circle are the centres 
from which all the teeth curves may be drawn. The 
compasses are set to a radius equal to the pitch, less 
one-half the thickness of the tooth, and from a 
centre, as R, two face curves, as F G, may be marked ; 
from the next centre, as at S, the curves D E may be 
marked, and so on for all the faces ; that is, the tooth 
curves lying between the outer circle X and the pitch 
circle P. For the flank curves, that Is, the curve from 
P to Y, the compasses are set to a radius equal to the 
pitch; and from the sides of the teeth the flank curves 
are drawn. Thus from J, as a centre flank, K Is drawn ; 
from V, as a centre flank, H is drawn, and so on. 

The proportions of the teeth for cast gears generally 
accepted in this country are those given by Professor 
Willis, as average practice, and are as follows; 

Depth to pitch line, j\ of the pitch- 
Working depth, 
Whole depth, 
Thickness of tooth. 
Breadth of space, 

Instead, however, of calculating the dimensions 
these proportions give for any particular pitch, a dia- 
gram or scale may be made from which they may be 
taken for any pitch by a direct application of the 
compasses. A scale of this kind is given in P'igure 



To 

7 
TO 

5 
TT 

6 
TT 



35. 1 



n which the line A B is divided into inches and 



parts to represent the pitches; its total length repre- 
senting the coarsest pitch within the capacity of the 
scale; and the line B C (at a right-angle to A B) the 



\x 



LA, 



jq5 mechanical drawing SELF-TAUGHT. 

whole depth of the tooth for the coarsest pitch, being 
t'o of the length of A B. 



2.0 — fbs per Inch Breadth of Face 
30 
,4.0 
50 




<322 



Depth of Pitch Line 

\^ 

' Thickness of Tooth 



Width of Space 



' _ Working Depth of Tooth 



_Wh olcJD epth^ of Toot^^ 



^''^'i' ■^'^^■ 



The other dlai^onal lines are for the proportion o^ 
the dimensions marked on the fiourc. Thus th(^ 



DRAWING GEAR WHEELS, 



197 



depth of face, or distance from the pitch line to the 
extremity or tooth point for a 4 inch pitch, would 
be measured along the line B C, from the vertical line 
B to the first diaoronal. The thickness of the tooth 
would be for a 4 inch pitch along line B C from B to 
the second diagonal, and so on. For a 3 inch pitch 
the measurement would be taken alone the horizontal 
line, starting from the 3 on the line A B, and so on. 
On the left of the diagram or scale is marked the lbs, 
strain eacfi pitch will safely transmit per inch width 
of wheel face, accordinor to Professor Marks. 




Fig. 236. 

The application of the scale is as follows: The pitch 
circles P P and P' P', Figure 236, for the respective 
wheels, are drawn, and the height of the teeth is ob- 
tained from the scale and marked beyond the pitch 
circles, when circles O and O' may be drawn. Sim- 
ilarly, the depths of the teeth within the pitch circles are 
obtained from the scale or diagram and marked within 
the respective pitch circles, and circles R and R' are 
marked in. The pitch circles are divided oft' into as 
many points of equal division, as at a, b, <r, dy e, etc., as 
the respective wheels are to have teeth, and the thick- 
ness of tooth having been obtained from the scale, this 



I^g MECHANICAL DRAWING SELF-TAUGHT. 

thickness Is marked from the points of division on the 
pitch circles, as at/" In the figure, and the tooth curves 
may then be drawn In. It may be observed, however, 
that the -tooth thicknesses will not be. strictly correct, 
because the scale gives the same chord pitch for the 
teeth on both wheels w^iich will oive different arc 
pitches to the teeth on the two wheels; w^iereas, It is 
the arc pitches, and not the chord pitches, that should 
be correct. This error obviously increases as there 
is a ereater amount of difference between the two 
wheels. 

The curves given to the teeth in Figure 234 are 
not the proper ones to transmit uniform motion, but 
are curves merely used by draughtsmen to save the 
trouble of findlnor the true curves, which if it be re- 
quired, may be drawn with a very near approach to 
accuracy, as follows, which is a construction given by 
Rankine : 

Draw the rolling circle D, Figure 237, and draw A 
D, the line of centres. From the point of contact at 
C, mark on D, a point distant from C one-half the 
amount of the pitch, as at P, and draw the line P C of 
indefinite length beyond C. Draw the line P E passing 
through the line of centres at P2, which is equidistant 
between C and A. Then increase the length of line 
P F to the right of C by an amount equal to the 
radius A C, and then diminish it to an amount equal 
to the radius 1^: D, thus obtaining the point F, and tlie 
latter will be tlie location of centre for com[)asses to 
strike the lai:(^ curve. 

Another method of finding tlie face , curve, with 
compasses, is as follows: In Figure 238 let P P rep- 



DRAiriXG GEAR WHEELS. 



99 



resent the pitch circle of tlie wheel to be marked, and 
B C the path of the centre of the orenerating or de- 




scribing circle as it rolls outside of P P. Let the 
point B represent the centre of the generating circle 




when it is in contact with the pitch circle at A. Then 
from B mark off, on B C, any number of equidistant 



k 



200 MECHANICAL DRAWING SELF-TAUGHT. 

points, as D, E, F, G, H, and from A mark on the 
pitch circle, with the same radius, an equal number of 
points of division, as i, 2, 3, 4, 5. With the pom- 
passes set to the radius of the generating circle, that 
is, A B, from B, as a centre, mark the arc I, from D, 
the arc J, from E, the arc K, from F, and so on, mark- 
ing as many arcs as there are points of division on B 
C. With the compasses set to the radius of divisions 
I, 2, etc., step off on arc M the five divisions, N, O, 
S, T, V, and at V will be a point on the epicycloidal 
curve. From point of division 4, step off on L four 




Fig. 239. 

points of division, as a, b, c, d ; and ^ will be another 
point on the epicycloidal curve. From point 3, set 
off three divisions, and so on, and through the points 
so obtained draw by hand, or with a scroll, the curve. 
Hypocycloids for the Hanks of the teeth maybe traced 
in a similar manner. Thus in Figure 239, PP is the 
pitch circle, and B C the line of motion of the centre 
of the generating circle to 'be rolled widiin P P. From 
1 to 6 are points of equal division on the pitch circle, 
and D to I are arc locations for the centre of the gen- 



DRAWIXG GEAR WHEELS. 201 

erating circle. Starting from A, which represents the 
location for the centre of the generating circle, the 
point of contact between the generating and base cir- 
cles will be at B. Then from i to 6 are points of 
equal division on the pitch circle, and from D to I are 
the corresponding locations for the centres of the gen- 
erating circle. From these centres the arcs J, K, L, 
M, N, O, are struck. The six divisions on O, from a 
to f, give at y a point in the curve. Fixe divisions 
on N, four on M, and so on, give, respectively, points 
in the curve. 

There is this, however, to be noted concerning the 
construction of the last two fieures. Since the circle 
described by the centre of the generating circle is 
of a different arc or curve to that of the pitch circle, 
the length of an arc having an equal radius on each 
will be different. The amount is so small as to be 
practically correct. The direction of the error is to 
give to the curves a less curvature, as though they 
had been produced by a generating circle of larger 
diameter. Suppose, for example, that the difference 
between the arc a, b, and its chord is .i, and. that the 
difference between the arc 4, 5, and its chord is .01, 
then the error in one step is .09, and, as the pointy 
is formed in five steps, it will contain this error multi- 
plied five times. Point d would contain it multiplied 
three times, because it has three steps, and so on. 

The error will increase in proportion as the diame- 
ter of the generating is less than that of the pitch 
circle, and though in large wheels, working with large 
w^heels, so that the difference between the radius of 
the creneratino- circle and that of the smallest wheel is 



202 



MECHANICAL DRAWING SELF-TAUGHT. 



i 



not excessive, it is so small as to be practically inap- 
preciable, yet in small wheels, working with large 
ones, it may form a sensible error. 

For showinor the dimensions throuo^h the arms and 





Fig. 240. 

hub, a sectional view of a section of the wheel may be 
given, as in lML:ure 240, which represents a section of 
a wheel, and a j)inion, and on these two views all the 
necessary dimensions may be marked. 



X 



Il 



i 



/ 




J 






t 



ge 203.) 



J 



DRAWING GEAR WHEELS. 203 

If It Is desired to draw an ^Ag^ view of a wheel 
(which the student will find excellent practice), the 
lines for the teeth may be projected from the teeth in 
the side view, as in Figure 240 a. Thus tooth E is 
projected by drawing lines from the corners A, B, C, 
in the side view across the face in the edge view, as 
at A, B, C In the latter view, and similar lines may be 
obtained In the same way for all the teeth. 

When the teeth of wheels are to be cut to form in 
a gear-cutting machine, the thickness of the teeth is 
nearly equal to the thickness of the spaces, there being 
just sufficient difterence to prevent the teeth of one 
wheel from becoming locked in the spaces of the other; 
but when the teeth are to be cast upon the wheel, the 
tooth thickness is made less than the width of the 
space to an amount that is usually a certain propor- 
tion of the pitch, and is termed the side clearance. 
In all wheels, whether with cut or cast teeth, there is 
given a certain amount of top and bottom clearance ; 
that is to say, tlie points of the teeth of one wheel do 
not reach to the bottom of the spaces in the other. 
Thus in the Pratt and Whitney system the top and 
bottom clearance is one-eighth ot the pitch, while in 
the Brown and Sharpe system for involute teeth the 
clearance is equal to one-tenth the thickness of the 
tooth. 

In drawing bevil gear wheels, the pitch line of each 
tooth on each wheel, and the surfaces of the points, as 
well as those at the bottom of the spaces, must all 
point to a centre, as E in Figure 241, which centre is 
where the axes of the shafts would meet. It is unne- 
cessary to mark In the correct curves for the teeth, 



204 



MECHANICAL DRAWING SELF-TAUGHT. 



for reasons already stated, with reference to the curves 
for a spur wheel. But if it is required to do so, the 
construction to find the curves is as shown in Fieure 
242, in which let A A represent the axis of one shaft, 
and B that of the other of the pair of bevil wheels that 
are to work together, their axes meeting at W ; draw 
the line E at a right angle to A A, and representing 
the pitch circle diameter of one wheel, and draw F at 
a right angle to B, and representing the pitch circle of 
the other wheel ; draw the line G G, passing through 




Fig. 241. 

the point W and the point T, where the pitch circles 
or lines E F meet, and G G will be the line of contact 
of the tooth of one wheel upon the tooth of the other 
wheel ; or in other words, the pitch line of the tooth. 
Draw lines, as H and I, representing the tooth 
breadth. From W, as a centre, draw on each side of 
G G dotted lines, as P, representing the height of \\\^\ 
tooth above and below the pitch line G G. At a riglu 
angle to G G draw the line J K ; and from where this 
line meets B, as at O, mark the arc a, which will repre- 
sent the pitch circle for die large diameter of the pinion 



DA'AU'IXG GEAR WHEELS. 



20; 



D. [The smallest wheel of a pair of gears is ternied 
the pinion.] Draw the arc b for the height, and circle c 
for the depth of the teeth, chus defining the height of 
the tooth at that end. Similarly from P, as a centre 
mark (for the large diameter of wheel C,) arcs g, h, 




Fig. 242. 



and {, arc g representing the pitch circle, i the height, 
and h the depth of the tooth. On these arcs draw 
the proper tooth curves in the same manner as for 
■spur wheels; that is, obtain the curves by the construe- 



2o6 MECHANICAL DRAWING SELF-TAUGHT. 

tion shown In Figures 237, or by those In Figures 238 
and 239. 

To obtain the arcs for the other end of the tooth, 
draw Hne M M parallel to line J K; set the compasses 
to the radius R L, and from P, as a centre, draw the 
pitch circle k. For the depth of the tooth draw the 
dotted line p, meeting the circle h and the point W. 
A similar line, from i to W, will give the height of the 
tooth at its Inner end. Then the tooth curves may be 
drawn on these three arcs, ky /, m, In the same as If 
they were for a spur wheel. 

Similarly for the pitch circle of the inner and 
small end of the pinion teeth, set the compasses to 
radius S L, and from O as a centre mark the pitch 
circle d. Outside of d mark e for the height above 
pitch lines of the tooth, and inside of d mark the arc 
f for the depth below pitch line of the tooth at that 
end. The distance between the dotted lines as p, rep- 
resents the full height of the tooth ; hence h meets /, 
which is the root of the tooth on the laree wheel. To 
give clearance and prevent the tops of the teeth on 
one wheel from bearlnsf ao-alnst the bottoms of the 
spaces in the other wheel, the point of the pinion 
teeth is marked below ; thus arc b does not meet Ji or 
p, but Is short to the amount of clearance. Having 
obtained the arcs dy e,f, the curves may be marked 
thereon as for a spur wheel. A tooth thus marked Is 
shown at x, and from Its curves between /; and c, a 
template may be made for the large diameter or outer 
end of the pinion teeth. Similarly for the wheel C 
the outer end curves are marked on the arcs ^^, //, /, 
and those for tlu^ other end of the tooth are marked 
between the arcs /, ;;/. 




Fig. 243 




■fe 207.) 

It 



DRAWING GEAR WHEELS. 



207 



Figure 243 represents a drawing of one-half of a 
bevil gear, and an edge view projected from the same. 
The point E corresponds to point E in Figure 241, or 
W in 242. The Hne F shows that the top surface of the 
teeth points to E. Line G shows that the pitch line 
of each tooth points to E, and lines H show that the 
bottom of the surface of a space also points to E. 
Line i shows that the sides of each tooth point to £. 
And it follows that the outer end of a tooth is both 
higher or deeper and also thicker than its inner end; 




thus J Is thicker and deeper than end K of the tooth. 
Lines F G, representing the top and bottom of a tooth 
in Figure 243, obviously correspond to dotted lines/ 
in Flo-ure 242. The outer and inner ends of the teeth 
in the edge view are projected from the outer and 
inner ends In the face view, as is shown by the dotted 
lines carried from tooth L In the face view, to tooth L 
in the edge view, and it is obvious from what has been 
said that In drawing the lines for the tooth In the edge 
view they will point to the centre E. 



I 



208 



MECHANICAL DRAWING SELF-TAUGHT. 



To save work In drawing bevil gear wheels, they 
are sometimes drawn In section or In outHne only; 
thus In Figure 244 Is shown a pair of bevU wheels 
shown In section, and In Figure 245 Is a drawing of a 
part of an Ames lathe feed motion. BCD and E 
are spur gears, while G H and I are bevil gears, the 




cone surface on which the teeth lie being left blank, 
save at the edges where a tooth is in each case drawn 
in. Wheel D is shown in section so as to show the 
means by wliich it may be moved out of gear with C 
nnd 1'^. Small bevil gears may also be represented by 
simple line shading; thus in Figure 247 the two 
bodies A and C would readily be understood to be a 
bevil gear and i)inIon. Similarly small spur wheels 




Fit?. 251. (Page 209.) 



VKAUVXC GEAR WHEELS. 



209 



may be represented by simple circles in a side view 
and by line shading- in an edge view ; thus it would 
answer every practical purpose if such small wheels 

K 



/Ol B 




as in Figures 246 and 247 at D, F, G, K, P, H, I and 
J, were drawn as shown. The pitch circles, how- 
ever, are usually drawn in red ink to distinguish 
them. 

Q 




^Hl_^i 



In Figure 248 Is an example in which part of the 
o^ear is shown with teeth in, and the remainder is illus- 
trated by circles. 

In Figure 250 is a drawing of part of the feed n^io- 
tions of a Niles Tool Works horizontal boring mill, 
Figure 251 being an end view of the same. / is a fric- 
tion disk, and g a friction pinion, g' is a rack, F is a 
14 



2IO 



MECHANICAL DRAWING SELF-TAUGHT. 



feed-screw, / is a bevil pinion, and q a bevil wheel; z, 
m, 0, are gear wheels, and J a worm operating a 
worm-pinion and the gears shown. 

Figure 249 represents three bevil gears, the upper 
of which is line shaded, forming an excellent example 
for the student to copy. 

The construction of oval gearing is show^n in 




Fiff. 248. 



Figures 252, 253, 254, 255, and 256. The pitch-circle 
is drawn by the construction for drawing an ellipse 
that was given with reference to Figure Si, but as 
that construction is by means of arcs of circles, and 
tlierefore not strictly correct, Professor IMcCord, in an 
iirticle on clliplical gearing, says, concerning it and 
the construction of oval gearing generally, as follows: 
"But these circular arcs maybe rectified and sub- 



jj 




Fig. 249. (Page 210.) 



DKAiy/XG GEAR WHEELS. 



211 




Fig. 250. 



?A2 



MECHANICAL DRAWING SELF-TAUGHT. 



divided with great facility and accuracy by a very 
simple process, which we take from Prof. Rankine's 
"Machinery and Mill Work," and is illustrated in Fig- 
ure 252. Let O B be tangent at O to the arc O D, 
of which C is the centre. Draw the chord D O, bisect 
it in E, and produce it to A, making O A=0 E; with 
centre A and radius A D describe an arc cutting the 
tangent in B; then O B will be very nearly equal in 
length to the arc O D, which, however, should not 




Fig. 252. 



exceed about 60 degrees; if it be 60 degrees, the 
error is theoretically about ^00 of the length of the arc, 
O B being so much too short; but this error varies with 
the fourth power of the angle subtended by the arc, 
so that for 30 degrees it is reduced to ^u of that 
amount, that is, to ttIod. Conversely, let O B be a tan- 
gent of given length; make OV=^}^ O B; then with 
centre F and radius FB describe an arc cutting the 
circle ODG (tangent to OB at O) In the point D; 
then OD will be approximately equal to Oil the 



D RAWING GEAR WHEELS, 



21^ 



error being the same as in the other construction and 
followino- the same law. 

The extreme simplicity of these two constructions 
and the facIHty with which they may be made with or- 




Fig. 253. 

dinary drawing instruments make them exceedingly 
convenient, and they should be more widely known 
than they are. Their application to the present 
problem Is shown in Figure 253, which represents a 



214 



MECHANICAL DRAWING SELF-TAUGHT. 



quadrant of an ellipse, the approximate arcs C D, 
E, E F, FA havine been determined bv trial and 
error. In order to space this off, for the positions of 
the teeth, a tangent is drawn at D, upon which is con- 
structed the rectification of D C, which is D G, and 
also that of D E in the opposite direction, that is, D 
H, by the process just explained. Then, drawing- the 
tangent at F, we set off in the same manner F I=F E, 




and F K == F A, and then measuring H L =::= I K. we 
hav(! finally G L, equal to the whole quadrant of the 
ellipse. 

Let It now be required to lay out twenty-four teeth 
upon this ellipse; that is, six In each quadrant; and 
for symmetry's sake we will suppose that the centre 
of one tooth Is 1o be at A, and that of another at C, 



DRAWING GEAR WHEELS. 215 

Figure 253. We, therefore, divide LG into six equal 
parts at the points i, 2, 3, etc., which will be the 
centres of the teeth upon the rectified ellipse. It 
is practically necessary to make the spaces a little 
greater than the teeth ; but if the greatest attainable 
exactness in the operation of the wheels is aimed at, 
it is important to observe that backlash, In elliptical 
gearing, has an effect quite different from that result- 
ing in the case of circular wheels. When the pitch- 
curves are circles, they are always in contact ; and we 
may, if we choose, make the tooth only half the 
breadth of the space, so long as its outline is correct. 
WHien the motion of the driver is reversed, the fol- 
lower will stand still until the backlash is taken up, 
when the motion will go on with a perfectly constant 
velocity ratio as before. But in the case of two ellip- 
tical w^heels, if the follow^er stand still while the driver 
moves, which must happen w^hen the motion is re- 
versed if backlash exists, the pitch-curves are thrown 
out of contact, and, although the continuity of the 
motion will not be interrupted, the velocity ratio w^ill be 
affected. If the motion is never to be reversed, the per- 
fect law of the velocity ratio due to the elliptical pitch- 
curve may be preserved by reducing the thickness of 
the tooth, not equally on each side, as is done in cir- 
cular wheels, but wholly on the side not in action. 
But if the machine must be capable of acting indiffer- 
ently In both directions, the reduction must be miade 
on both sides of the tooth: evidently the action will be 
slightly impaired, for w^hich reason the backlash should 
be reduced to a minimum. Precisely what is the 
minimum is not so easy to say, as it evidently depends 



2i6 MECHANICAL DRAWING SELF-TAUGHT. \ 

much Upon the excellence of the tools and the skill of 
the workman. In many treatises on constructive j 
mechanism it is variously stated that the backlash ] 
should be from one-fifteenth to one-eleventh of the 
pitch, which would seem to be an ample allowance in 
reasonably good castings not intended to be finished, 
and quite excessive if the teeth are to be cut; nor is 
it very obvious that its amount should depend upon 
the pitch any more than upon the precession of the 
equinoxes. On paper, at any rate, we may reduce it 
to zero, and make the teeth and spaces equal in 
breadth, as shown in the figure, the teeth being indi- 
cated by the double lines. Those upon the portion 
L H are then laid off upon K I, after w^hich these di- 
visions are transferred to the ellipse by the second of 
Prof. Rankine's constructions, and w'e are then ready 
to draw the teeth. 

The outlines of these, as of any other teeth upon 
pitch-curves which roll together in the same plane, 
depend upon the general law that they must be such 
as can be marked ou-t upon the planes of the curves, 
as they roll by a tracing-point, which is rigidly con- 
nected with and carried by a third line, moving in 
rolling contact with both the pitch-curves. And since 
under that condition the motion of this third line, rela- 
tively to each of the others, is the same as thougli it 
rolled along each of them separately while they re- 
mained fixed, tlie process of constructing tlie gener- 
ated curv(^s becomes comparatively simplc\ For the 
describing \\x\(\ \\k\ naturally select a circle, which, in 
order to fulfil the condition, must be small enough to 
roll within the pitcli ellipse; its tliameter is dc^termined 



DRAIVIXG GEAR WHEELS. 



217 



by the consideration that if it be equal to A P, the 
radius of the arc A F, the flanks of the teeth in that 
region will be radial. We have, therefore, chosen a 
circle whose diameter, A B, is three-fourths of A P, 
as shown, so that the teeth, even at the ends of the 
wheels, will be broader at the base than on the pitch 
line. This circle ought strictly to roll upon the true 
elliptical curve ; and assuming, as usual, the tracing- 
point upon the circumference, the generated curves 
would vary slightly from true epicycloids, and no two 
of those used in the same quadrant of the ellipse 
w^ould be exactly alike. Were it possible to divide 
the ellipse accurately,- there would be no difficulty in 
laying out these curves ; but having substituted the 
circular arcs, we must now roll the generating circle 
upon >these as bases, thus forming true epicycloidal 
teeth, of which those lying upon the same approxima- 
ting arc will be exactly alike. Should the junction of 
two of these arcs fall within the breadth of a tooth, as 
at D, evidently both the face and the flank on one 
side of that tooth will be different from those on the 
other side; should the junction coincide with the edge 
of a tooth, w^iich is very nearly the case at F, then the 
face on that side will be the epicycloid belonging to 
one of the arcs, its flank a hypocycloid belonging to 
the other; and it is possible that either the face or the 
flank on one side should be generated by the rolling 
of the describing circle pardy on one arc, partly on 
the one adjacent, which, upon a large scale, and where 
the best results are aimed at, may make a sensible 
change in the form of the curve. 

The convenience of the constructions given in Fig- 



2i8 MECHANICAL DRAWING SELF-TAUGHT. 

ure 252 is nowhere more apparent than In the draw- 
ing of the epicycloids, when, as in the case in hand, 
the base and generating circles may be of incommen- 
surable diameters ; for which reason we have, in Fig- 
ure 254, shown its application in connection with the 
most rapid and accurate mode yet known of describ- 
ine those curves. Let C be the centre of the base 

o 

circle ; B, that of the rolling one ; A, the point of con- 
tact. Divide the semi-circumference of B into six 
equal parts at i, 2, 3, etc. ; draw the common tangent 
at A, upon which rectify the arc A2 by process No. 1 ; 
then by process No. 2 set out an equal arc A2 on the 
base circle, and stepping it off three times to the right 
and left, bisect these spaces, thus making subdivisions 
on the base circle equal in length to those on the roll- 
ing one. Take in succession as radii the chords Ai, 
A2, A3, etc., of the describing circle, and with centres 
I, 2, 3, etc., on the base circle, strike arcs either exter- 
nally or internally, as shown respectively on the right 
and left; the curve tangent to the external arcs is the 
epicycloid, that tangent to the internal ones the hypo- 
cycloid, forming the face and flank of a tooth for the 
base circle. 

In the diagram, Figure 253, we have shown a part 
of an ellipse whose length is ten Inches, and breadth 
six, the figure being half size. In order to give an 
idea of tlic actual appearance of tlie ccMublnation when 
comj)l('te, we show In b^igurc^ 255 the pair in gc^r, on 
a scale of three inches to the foot. Tlie excessive 
eccentricity was selected merel)' for the purjx)se of 
illustration. iMgiire 255 will serve also to call atten- 
tion to another serious circumstance, whi» h is, that 



DRAWIXG GEAR WHEELS. 



2irj 



although the ellipses are alike, the wheels are not; 
nor can they be made so if there be an even number 
of teeth, for the obvious reason that a tooth upon one 
wheel must fit into a space on the other ; and since in 
the first wheel, Figure 255, we chose to place a tooth 
at the extremity of each axis, we must in the second 
one place there a space instead ; because at one time 




the major axes must coincide : at another, the minor 
axes, as In Figure 255. If, then, we use even num- 
bers, the distribution, and even the forms of the teeth, 
are not the same in the two wheels of the pair. But 
this complication may be avoided by using- an odd 
number of teeth, since, placing a tooth at one extrem- 
ity of the major axes, a space will come at the other. 



220 



MECHANICAL DRAWING SELF-TAUGHT. 



It is not, however, always necessary to cut teeth all 
round these wheels, as will be seen by an examination 
of Figure 256, C and D being the fixed centres of the 
two ellipses in contact at P. Now P must be on the 
line C D, whence, considering the free foci, we see 
that P B is equal to PC, and PA to P D; and the 
common tangent at P makes equal angles with C P 
and P A, as is also with P B and P D ; therefore, C D 




Fig. 256. 

being a straight line, A B is also a straight line and 
equal to C D. If then the wheels be overhung, that 
is, fixed on the ends of the shafts outside the bearings, 
leaving the outer faces fre(\ the moving foci may be 
connected by a rigid link A B, as shown. 

This link will tlicn communicate the same morion 
that would resuh fVom the use of the complete ellip- 



DRAWING GEAR WHEELS. 221 

tical wheels, and we may therefore dispense with the 
most of the teeth, retaining only those near the ex- 
tremities of the major axes, which are necessary in 
order to assist and control the motion of the link 
at and near the dead-points. The arc of the pitch- 
curves through which the teetli must extend will vary 
with their eccentricity; but In many cases it would not 
be greater than that which in the approximation may 
be struck about one centre ; so that, in fact, it would 
not be necessary to go through the process of rectify- 
ing and subdividing the quarter of the ellipse at all, 
as in this case it can make no possible difference 
whether the spacing adopted for the teeth to be cut 
would "come ou-t even" or not, if carried around the 
curve. By this expedient, then, we may save not only 
the trouble of drawing, but a great deal of labor in 
making, the tee thround the whole ellipse. We might 
even omit the intermediate portions of the pitch 
ellipses themselves; but as they move in rolling con- 
tact their retention can do no harm, and in one part 
of the movement will be beneficial, as they will do 
part of the work; for if, when turning, as shown by 
the arrows, we consider the wheel whose axis is D as 
the driver, It will be noted that its radius of contact; 
C P, Is on the increase; and so long as this Is the case 
the other wheel will be compelled to move by contact 
of the pitch lines, although the link be omitted. And 
even if teeth be cut all round the wheels, this link is 
a comparatively inexpensive and a useful addition to' 
the combination, especially if the eccentricity be con- 
siderable. Of course the wheels shown In Figure 255 
might also have been made alike, by placing a tooth 



222 MECHANICAL DRAWING SELF-TAUGHT. 

at one end of the major axis and a space at the other, 
as above suggested. In regard to the variation in the 
velocity ratio, it will be seen, by reference to Figure 
256, that if D be the axis of the driver, the follower 
will in the position there shown move faster, the ratio of 

P D 

the ancrular velocities beinof ; if the driver turn 

PB 
uniformly, the velocity of the follower will diminish, 
until at the end of half a revolution, the velocity ratio 

PB 
will be ; in the other half of the revolution these 

PD 
changes will occur in a reverse order. But P D = L 
B; if then the centres B D are given in position, we 
know L P, the major axis; and in order to produce 
any assumed maximum or minimum velocity ratio, we 
have only to divide L P into segments whose ratio is 
eoual to that assumed value, which will eive the foci 
of the ellipse, whence the minor axis may be found 
and the curve described. For instance, in Figure 255 
the velocity ratio being nine to one at the maximum, 
the major axis is divided into two parts, of which one 
is nine times as lono- as the other; in Fii^ure 256 the 
ratio is as one to three, so that the major axis being 
divided into four parts, the distance A C between the 
foci is equal to two of them, and the distance of either 
focus from the nearest extremity of the major axis is 
equal to one, and from the more remoter extremity is 
equal to three of tluNse parts. 



CHAPTER XII. 
PLOTTING MECHANICAL MOTIONS. 

Let it be required to find how much motion an 
eccentric will give to its rod, the distance from the 
centre of its bore to the centre of the circumference, 
which is called the throw, being the distance from A 
to B in Figure 257. Now as the eccentric is moved 




around by the shaft, it is evident that the axis of its 
motion will be the axis A of the shaft. Then from A 
as a centre, and with radius from A to C, we draw the 
dotted circle D, and from E to F will be the amount 
of motion of the rod in the direction of the arrow. 

(2^3) 



224 



MECHANICAL DRAWING SELF-TAUGHT. 



This becomes obvious if we suppose a lead pencil 
to be placed against the eccentric at E, and suppose 
the eccentric to make half a revolution, whereupon 
the pencil will be pushed out to F. If now we measure 
the distance from E to F, we shall find it is just twice 
that from A to B. We may find the amount of motion, 
however, in another way, as by striking- the dotted 
half circle G, showing the path of motion of B, the 
diameter of this path of motion being the amount of 
lateral motion given to the rod. 

In Figure 258 is a two arm lever fast upon the 




Fig. 258. 

same axis or shaft, and it is required to find how much 
a given amount of motion of the long arm will move 
the short one. Suppose the distance the long arm 
moves is to A. Then draw the line B from A to the 
axis of the shaft, and the line C the centre line of the 
long arm. From the axis of the shaft as a centre, 
draw the circle 1), passing through the eye or centre 
I'^ of the short arm. Take tlie radius from V to G, 
and from E as a centre mark It on 1) as at H, and H 
is wluM'e Ii will be when the lonjj' arm moves to A. 



r LOTTING MECIIAXICAL MOTIONS. 22$ 

We have here simply decreased the motion in the 
same proportion as one arm Is shorter than the other. 
The principle involved Is to take the motion of both 
arms at an equal distance from their axis of motion, 
which is the axis of the shaft S. 

In Figure 259 we have a case In which the end of a 




Fig. 259. 



lever acts directly upon a shoe. Now let it be re- 
quired to find how much a given motion of the lever 
will cause the shoe to slide along the linear; the point 
H is here found precisely as before, and from it as a 
centre, the dotted circle equal in diameter to the small 
circle at E Is drawn from the perimeter of the dotted 
circle, a dotted line is carried up and another is car- 
ried up from the face of the shoe. The distance K 
between these dotted lines Is the amount of motion of 
the shoe. 

In Figure 260 we have the same conditions as in Fig- 
ure 259, but the short arm has a roller acting against a 
larger roller R. The point H Is found as before. The 
amount of motion of R is the distance of K from J ; 
hence we may transfer this distance from the centre of 
15 



226 



MECHANICAL DRAWING SELF-TAUGHT. 



R, producing the point P, from which the new position 
may be marked by a dotted circle as shown. 




Fig. 260. 

\Vi Figure 261a h'nk is introduced in place of the rol- 
ler, and it is required to find the amount of motion of 
rod R. The point^H is found as before, and then the 
length from centre to centre of link L is found, and 
with this radius and from H as a centre the arc P 




Fig. 261. 

is drawn, and where P intersects the centre line J of 
R is the new position for the eye or centre O of R. 

In l^^igure 262 we have a case of a similar lever actua- 
ting a plunger in a vertical line, it being required to find 
how mucli a givcm amount of motion of the long arm will 
actuate the pli.nger. Suppose the long arm to move 



PLOTTING MECHANICAL MOTIONS. 



227 



to A, then draw the Hnes B C and the circle D. Take 
the radius or distance F, G, and from E mark on D 
the arc H. Mark the centre hne J of the rod. Now 
take the leno^th from E to I of the hnk, and from H as 




Fig. 262. 

a centre mark arc K, and at the intersection of K 
with J is where the eye I will be when the long arm 
has moved to A. 

In Figure 263 are two levers upon their axles or 
shafts S and S' ; arm A is connected by a link to arm 
B, and arm C is connected direct to a rod R. It is re- 
quired to find the position of centre G of the rod eye 
when D is in position E, and when It is also In position 
F. Now the points E and F are, of course, on an arc 
struck from the axis S, and it is obvious that in what- 
ever position the centre H may be it will be some- 
where on the arc I, I, which is struck from the centre 
S'. Now suppose that D moves to E, and if we take 



i 



228 MECHANICAL DRAWING SELF-TAUGHT. 

the radius D, H, and from E mark it upon the arc I as 
at V, then H will obviously be the new position of H. 
To find the new position of G we first strike the arc 
J, J, because in every position of G it will be some- 
where on the arc J, J. To find where that will be 
when H is at V, take the radius H, G, and from V as 




Fig. 263. 

a centre mark it on J, J, as at K, which is the position 
of G when D is at E and H is at V. For the posi- 
tions when D is at F we repeat the process, taking the 
radius D, H, and from F marking- P, and with the 
radius H, G, and from P as a centre marking Q ; then 
P is the new position for H, and Q is that for G. 

In Figure 264 a lever arm A and cam C are in one 
piece on a shaft. S is a shoe sliding on the line .r, 
and held against the cam face by the rod R; it is 
required to find the position of the face of the shoe 
against the cam when the end of the arm is at D. 



P LOTTING MECHANICAL MOTIONS. 



229 



Draw line E from D to the axis of the shaft and 
line F. From the shaft axis as a centre draw circle 
W; draw line J parallel to x. Take the radius G H, 
and from K as a centre mark point P on W ; draw 
line O from the shaft axis through P, and mark point 
T. From the shaft axis as a centre draw from T an 
arc, cutting J at V^, and V is the point where the face 
of the shoe and the face oi the cam will touch when 
the arm stands at D. 

Let it be required to find the amount of motion im- 
parted in a straight line to a rod attached to an eccen- 




Fig. 264. 

trie strap, and the following construction may be used. 
In Figure 265 let A represent the centre of the shaft, 
and, therefore, the axis about which the eccentric re- 
volves. Let B represent the centre of the eccentric, 
and let it be required to find in what position on the 
line of motion x, the centre C of the rod eye will be 
when the centre B of the eccentric has moved to E. 
Now since A is the axis, the centre B of the eccentric 
must rotate about it as denoted by the circle D, and 
all that is necessary to find the position of C for any 
posidon of eccentric is to mark the posidon of B on 
circle D, as at E, and from that position, as from E, 



230 



MECHANICAL DRAWING SELF-TAUGHT. 



as a centre, and with the length of the rod as a radius, 
mark the new position of C on the Hne x of its mo- 
tion. Vv^ith the centre of the eccentric at B, the hne 
Q, representing the faces of the straps, will stand at a 
right angle to the line of motion, and the length of the 
rod is from B to C ; when the eccentric centre moves 
to E, the centre line of the rod will be moved to posi- 
tion P, the line Q will have assumed position R, and 
point C will have moved from its position In the draw- 



Fig. 265. 

ing to G on line x. If the eccentric centre be sup- 
posed to move on to F, the point C will move to H, 
the radii B C, E G, and F H all being equal in length. 
Now wlien the eccentric centre is at E it will have 
moved one-tjuarter of a revolution, and yet the point C 
will only have moved to G, whicli is not central be- 
tween C and 11, as is denoted by the dotted half 
circle I. 

On the other hand, while tlu^ eccentric centre Is. 




PLOTTIXG MECHANICAL MOTIONS. 



23^ 



moving from E to F, which is but one-quarter of a 
revolution, the rod end Avill move from G to H. This 
occurs because the rod not only moves endwise, but 
the end connected to the eccentric strap moves to- 
wards and away from the line x. This is shown in 
the fio^ure, the rod centre line beine marked in full line 
from B to x. And when B has moved to E, the rod 
centre line is marked by dotted line E, so that it has 
moved away from the line of motion B x. In Figure 
266 the eccentric centre is shown to stand at an ang^le 




J K G 



Fig. 266. 



of 45 degrees from line ^, which is at a right angle 
to the line of motion x x, and the position of the rod 
end is shown at C, J and H representing the extremes 
of motion, and G the centre of the motion. 

If now we suppose the eccentric centre to stand at 
T, which is also an angle of 45 degrees to ^, then the 
rod end will stand at K, which is further away from G 
than C is: hence w^e find that on account of the move- 



232 MECHANICAL DRAWING SELF-TAUGHT. 

ment of the rod out of the straight end motion, the 
motion of the rod end becomes irregular in proportion 
to that of the eccentric, whose action in moving the 
eye C of the rod in a straight Hne is increased (by the 
rod) while it is moving through the half rotation de- 
noted by V in figure, and diminished during the other 
half rotation. 

In many cases, as, for example, on the river steam- 
boats in the Western and Southern States, cams are 
employed instead of eccentrics, and the principles in- 
volved in drawing or marking out such cams are given 
in the following remarks, which contain the substance 
of a paper read by Lewis Johnson before the American 
Society of Mechanical Engineers. In Figure 267 is a 
side view of a pair of cams; one, C, being a full stroke 
cam for operating the valve that admits steam to the 
engine cylinder ; and the other, D, being a cam to cut 
off the steam supply at the required point in the engine 
stroke. The positions of these cams with relation to 
the position of the crank-pin need not be commented 
upon here, more than to remark that obviously the 
cam C must operate to open the steam inlet valve in 
advance of cam D, which operates to close it and 
cause the steam to act expansively in the cylinder, and 
that the ano^le of the throw line of the cut-off valve D 
to the other cam or to the crank-pin varies according 
as it is required to cut off the steam either earlier or 
later in the stroke; 

The cam yoke is composed of two halves, Y and 
Y', bolted together by bolts B, which have a collar at 
one end and two nuts at the other qx\(\, the inner nuts 
N N enabling the letting together of the two halves 



PLOTTIXG MECHANICAL MOTIONS. 



233 




Fig. 267. 



234 MECHANICAL DRAWING. SELF-TAUGHT. 

of the yoke to take up the wear. It is obvious that 
as the shaft revolves and carries the cam with it, it 
will, by reason of its shape, move the yoke back and 
forth; thus, in the position of the parts shown in Figure 
267, the direction of rotation being denoted by the 
arrow, cam C will, as it rotates, move the yoke to the 
left, and this motion will occur from the time corner t? 
of the cam meets the face of Y' until corner b has 
passeH the centre line d. Now since that part of the 
circumference lying between points a and b of the 
cam is an arc of a circle, of which the axis of the shalt 
is the centre, the yoke will remain at rest until such 
time as b has passed line ^and corner a meets the jaw 
Y of the yoke ; hence the period of rest is determined 
by the amount of circumference that is made concen- 
tric to the shaft ; or, in other words, is determined by 
the distance between a and b. 

The object of using a cam instead of an eccentric is 
to enable the opening of the valves abruptly, at the 
beginning of the piston stroke, maintaining a uniform 
steam-port opening during nearly the entire length of 
stroke, and as abrupdy closing the valves at the termi- 
nation of the stroke. 

Figure 268 is a top view of the mechanism in Figure 
267 ; and Figure 269 shows an end view of the yoke. 
At R, in Figure 268, is shown a guide through which 
the yoke-stem passes so as to be guided to move in a 
straiQ:ht line, there beinor a oruide of this kind on eacli 
side of tlu! yoke, 

Th(i two cams are bolted to a collar that is secured 
to the crank-shaft, and are made in halves, as shown 
in the figures and also in Figures 270 and 271, which 



OD 



PLOTTING MECHANICAL MOTIONS. 2 

represent cams removed from the other mechanism. 

Fl 




Fig. 268. 
To enable a certain amount of adjustment of the cams 



236 



MECHANICAL DRAWING SELF-TAUGHT. 



Upon the collar, the bolts which hold them to the collar 
fit closely In the holes In the collar, but the cams are 
provided with oblong bolt holes as shown, so that the 
position of either cam, either with relation to the other 
cam or with relation to the crank-pin, can be adjusted 




Scale l'i=l foot 
Fig. 269. 

to the extent permitted by the length of the oblong 
holes. 

The crank Is assumed in the figures to be on Its 
dead centre nc^irest to the engine cylinder, and to rc- 
vnlx'c in the direction of the arrows. The cams are 



PLOTTING MECHANICAL MOTIONS. 



237 



SO arranged that their plain unflanged surfaces bolt 
against the collar. 

The method of drawincr or markinc^ out a full stroke 

o o 

cam, such as C in Figure 267, is illustrated in Figure 
272, in which the dimensions are assumed to be as 
follows : 

Diameter of crank shaft, 7^ inches; travel of cam, 
3 inches; width of yoke, 18 inches. 




Scale 1 '^ = 1 foot 
Fig. 270. 



The circumference of the cam is composed of four 
curved lines, P, F, K i, and K 2. The position of the 
centre of the crank shaft in this irregularly curved 
body is at X. The arcs K i and K 2 differ in radius, 
but are drawn from the same point, X, and hence are 
concentric with the crank shaft. 

The arcs P, P', are of like radius, but are drawn from 
the opposite points S, S, shown at the intersection of 



W 



238 



MECHANICAL DRAWING SELF-TAUGHT. 




■18— ,7- 

Scalc 1'^^ = 1 foot 



'<-%---> 



Fig. 271. 




Scale 1H_.1 foot 



PL O TTIA'G MECIIAXICAL MO TIOXS. 



^39 



the arcs P, P', with the arc K i. Thus arcs P, P', are 
eccentric to the crank shaft. 

To draw the cam place one point of the dividers at 
X, which is the centre of the crank shaft, and draw 
the circle E equal to v/iclth of yoke, i8 inches. 
Throuo-h this centre X, draw the two ricrht lines A 
and B. On the line B, at the intersection of the 
curved line E, draw the two vertical lines A i, A i. 
With a radius of lo^ inches, and with one point of 



is- 




273- 



the dividers at X, draw the arc K i. With a radius 
of 7^ inches, and one point of the dividers at X, 
draw the arc K 2. With a radius of i8 inches, and 
one point of the dividers at the intersection of the arc 
E, with the vertical line A i at S, draw the arc P opposite 
to S, and let it merge or lose itself in the curved line 
K 2. Draw the other curved line P' from the other 
point S, and we have a full stroke cam of the dimen- 



240 MECHANICAL DRAWING SELF-TAUGHT. 

sions required, and which is represented in Figure 273, 
removed from the hnes used in constructing it. 

The engravings from and including Figure 274 
illustrate the lines embracing cut-off cams of varying 




1/1 

vScnlo 1=^1 foot 
Fig. 274. 

limits of cut-off but all of like travel and dimensions, 
wliich are the same as those given for the full stroke 
cam in Mgurc 272. 



PLOTTING MECHANICAL MOTIONS. 



241 



In drawing cut-off cams, the stroke of the engine 
plays a part in determining their conformation, and in 
the examples shown this is assumed to be 4 feet. 
Figure 274 illustrates the manner of finding essential 
points in drawing or marking out cut-off cams. With 
X as a centre, and a radius of 2 feet, draw the circle 
E I, showing the path of the crank-pin in making a 





/ 


<^ 


.^ 


r 


,E 




k 


"^ 


\ 


f 






J? 


%. 


J 


\ 










ip^^ 


\ 


^::^ 






y^ 




\ 






A 


Scale 1>»^1 



Fig. 275. 

revolution. This circle has a diameter of 4 feet, equal 
to the stroke of the enorine. Draw the horizontal 
line B, passing through the centre of circle E i. 
Within the limits of circle E i, subdivide line B into 
eight equal parts, as at i, 2, 3, 4, etc. Draw the ver- 
tical lines, I, 2, 3, 4, etc., until they each intersect the 
circle E i. 

With X as a centre, draw the circle E, having a 
16 



242 



MECHANICAL DRAWING SELF-TAUGHT. 



diameter of i8 Inches, equal to the space in the yoke 
embracing the cam. 

From the centre X draw the series of radial lines 
through the points of Intersection of the vertical lines 
I, 2, 3, 4, etc., from the circle E i, and terminating at 



\ 



v^ 


V^ \ 


y^ 




_y 


\//:,X 


\ 


1/ + / 




// / /■ 


^v 


/ ^ / 


\ 


/ ^ 


\ 




^ ^ 


^ / f 




/ ^' '' 




/ N* 


^\ 


/ / 


■ 


' / 


/ 


/ 


/• 


• 


^;h.'' 


/ 

/ 


fe' / 




/' / 


' 


> y / 




\ / / 




X / 





Fig. 276. 

X. We will now proceed to utilize the scale afforded 
by F^igure 274, in laying off the cut-off cam shown in 
Figure 276. of half stroke limit. 

With X as a cc:ntre, draw the circle E, Figure 275, 
having a tliamctcr of 18 inchc^s. Bisect tills circle 
with lh(! straight lines A and B, which bear the same 



PLOTTING MECHANICAL MOTIONS. 



^43 



relation to their enclosing circle that the lines A, B, do 
to the circle E in Figure 274. 

It will be observed, in Figure 274, that the vertical 
line A is (at the top half) also No. 4, representing |, or 
half of the stroke. With a radius of 18 inches, and 
one point of the dividers placed at V, which is at the 
intersection of the circle E with the horizontal line B 




Scale l^^=lfoot 
Fig. 277. 

In Figure 275, draw the arc P. With the same radius 
and with one compass point rested at V ', draw the arc 
P'; then two arcs, P and P', intersecting at the point S. 
With the same radius and one point of the com- 
passes at S, draw the arc H H. The arcs K i and K 
2 are drawn from the centre X, with a radius of 10^ 
for K I and 7^ inches for K 2, and only serve in a 



244 



MECHANICAL DRAWING SELF-TAUGHT. 



half stroke cam to intersect the curved Hnes already 
drawn, as shown in Figure 275. In practice, the sharp 
corner at S would be objectionable, owing to rapid 
wear at this point; and hence a modification of the 
dimensions for this half stroke cam would be required 
to obtain a larger wearing surface at the point S, but 




Fig. 278. 

the cam of this limit (^ stroke) is correcdy drawn 
by the process described with reference to Figure 275, 
the outline of the cam so constructed being shown in 
Mgure 276. 

In Figure 278 is shown a cam designed to cut off 
the steam at five-eiglulis of the piston stroke, the con- 



PLOTTING MECHANICAL MOTIONS. 



245 



structlon lines being given in Figure 2 7 7, for which draw 
circle E and straight lines A and B, as in the preceding 
example. By reference to Figure 274 it will be ob- 
served that the diagonal line drawn throueh circle E at 
5 is drawn from the straight line marked 5, which inter- 
sects circle E i, and as this straight line 5 represents 
five-eighths of the stroke laid off on line B, it deter- 




Fig. 279. 

mines the limit of cut-off on the five-eighths cam in 
Figure 277. 

Turning then to Figure 274, take on circle E the 
radius from radial line 4 to radial line 5, and mark 
it in Figure 277 from the vertical line producing V'. 

Now, with a radius of 18 inches, and one point of 
the dividers fixed at point V, forming the Intersection 
of the circle E with the horizontal Ijne B, draw the arc 



i^ 



246 



MECHANICAL DRAWING SELF-TAUGHT. 



P. With the same radius, and one point of the dividers 
fixed at point V', draw the opposite arc P'. With a 
radius of 10^ inches from the centre X, draw the arc 
K I, intersecting Hnes P P', at S S. With a radius of 
^y^ inches, draw the curved hne K 2, opposite to 
curved Hne K i. Now, with a radius of 18 inches, 
and one point of the dividers fixed alternately at S S, 




Scale l^i=l foot 



draw the arcs H, H, from their intersection widi the 
circle E, until they merge into the curved line K 2. 
These curved lines embrace a cut-off cam of five- 
eighths limit, shown complete in Figure 278. 

l^^rom th(.' instructions already given it should be easy 
to understand that die three-fourths and sevcn-eii^hths 
cams, shown in iMgures 279, 280, 28 1 and 282, are 



PLOTTING MECHANICAL MOTIONS. 



247 



drawn by taking the points of their cut-off from the 
same scale shown in Figure 274, at the diagonal points 
6 and 7, intersecting circle E in that figure ; and cut-off 
cams of intermediate limit of cut-off can be drawn by 
further subdividing the stroke line B, in Figure 274, 
into the required limits. 

Cut-off cams of any limit are necessarily imperfect 
in their operations as to uniformity of cut-off from 




Fig. 281. 

opposite ends of the slides, not from any defect in the 
rule for laying them off, but from the well-known fact 
of the crank pin travelling a greater distance, while 
driven by the piston from the centre of the cylinder, 
through its curved path from the cylinder, over its 
centre, and back to the centre of the cylinder, than in 
accomplishing the remaining distance of its path in 
making a complete revolution ; and, although the sub- 



248 



MECHANICAL DRAWING SELF-TAUGHT. 



divisions of eighths of the stroke Hne B, in Figure 
274, does not truly represent a like division of the 
piston stroke, owing to deviation, caused by inclination 
of the connecting rod in traversing from the centres 
to half stroke, still it will be found that laying off a 
cut-off cam by this rule is more nearly correct than 
if the divisions on stroke line B were made to cor- 




Fig. 282. . 

respond exactly with a subdivision of piston stroke 
into eighths. 

The cut-off in cams laid off by the rules herein de- 
scribed Is greater in travelling from one side of the 
slides than in travelling from the opposite end, one 
cut-off being more than the actual cut-off of piston 
strok(,', and the other less ; and in practical use, owing 
to play or lost motion in the connections from cam to 



PLOTTING MECHANICAL MOTIONS. 



249 



valve, the actual cut-off is less than the theoretical ; 
hence cut-off cams are usually laid off to compensate 
that is, laid off with more limit ; for 



for lost motion 




i 



Fig. 283. 






instance, a five-eighths cam would be laid off to cut-off 
at eleven-sixteenths instead of five-eiorhths. 

o 

Figure 283 represents the motion a crank, C, im- 
parts to a connecting rod, represented by the thick 



250 MECHANICAL DRAWING SELF-TAUGHT. 

line R, whose end, B, Is supposed to be guided to move 
In a straight Hne. The circle H represents the path 
of the crank-pin, and dots i, 2, 3, etc., are 24 dif- 
ferent crank-pin positions equidistant on the circle of 
crank-pin revolution. Suppose the crank-pin to have 
moved to position i,and with the compasses set to the 
length of the rod R, we set one point on the centre of 
position I, and mark on the line of motion in the line 
a, which will be the position rod end B will have moved 
to. Suppose next that the crank-pin has moved into 
position 2, and with the compass point on the centre 
of 2 we mark line 2, showing that while the crank-pin 
moved from i to 2, the rod end moved from a X.ob ; by 
continuing this process we are enabled to discern the 
motion for the whole of the stroke. The backward 
stroke will be the same, for corresponding crank-pin 
positions, for both strokes ; thus, when the rod end Is 
at 7 the crank-pin may be at 7 or at 1 7. This fact 
enables us to find the positions for the positions later 
than 6, on the other side of the circle, as at 17, 16, 15, 
etc., which keeps the engraving clear. 

In Figure 284 a pinion, P, drives a gear-wheel, D, 
on which there is a pin driving the sliding die A in the 
link L, which is pivoted at C, and connected at its upper 
end to a rod, R. which is connected to a bolt, B, fast to 
a slide, S. It is required to find the motion of S, it 
moving in a straight line, dotted circle H' representing 
the path of the pin in the sliding die A, arc H repre- 
senting the line of motion of the upper end of link L, 
and lines N, O, Its centre line at the extreme ends of 
its vibrating motion. In Figure 285 the letters of ref- 
erence refer to the same i)arts as those in l^gure 284. 



PLOTTING MECHANICAL MOTIONS. 



2;i 



We divide the circle H' of pin motion into 24 equi- 
distant parts marked by dots, and through these we 



E 


A . 


\ 


i 


= 


= ( 


i — X 


^ ^ 




Fig. 284. 

draw lines radiating from centre, C, and cutting arc 
H, obtaining on the arc H the various positions for 
end Z of rod R, these positions being marked respec- 



252 



MECHANICAL DRAWING SELF-TAUGHT. 



lively I, 2, 3, 4, etc., up to 24. With a pair of com- 
passes set to the length of rod R from i on H, as a 
centre, we mark on the line of motion of the slide, line 
<3;, which shows where the other end of rod R will be 
(or in other words, it shows the position of bolt B in 
Figure 284), when the centre of A, Figure 284, is in 
position I, Figure 285. 

From 2 on arc H, we mark with the compasses line 
b on line M, showing that while the pin moved from i 
to 2, the rod R would move slide S, Figure 284, from 



ah c d € f g 



FonoardStrrike 
h i 



:L_i \ I I I iM 



Lackward Stroke 




Fig. 285. 

a W> d, in Figure 285. From 3 we mark c, and so on, 
all these marks being above the horizontal line M, 
representing the line of motion, and being for the for- 
ward stroke. For the backward stroke we draw the 
dotted line from position 17 up to arc H, and with the 
compasses at i 7 mark a line beneath the line M of 
motion, pursuing the same course for all the other 
I)In motions, as 18, 19, etc., until die pin arrives again 
at position 24, and the link at O, and has made a full 



PLOTTIXG MECHANICAL MOTIOXS. 



253 



revolution, and we shall have the motion of the forward 
stroke above and that of the backward one below the 
line of motion of the slide, and may compare the two. 




Fig. 286. 

Figures 286 and 287 represent the WHiitwortli quick 
return motion that is employed In many machines. F 
represents a frame supporting a fixed journal, B, on 



i^C 



254 



MECHANICAL DRAWING SELF-TAUGHT. 



which revolves a gear-wheel, G, operated by a pinion, 
P. At A is an arm having journal bearing in B at C. 
This arm is driven by a pin, D, fast in the gear, G ; 
hence as the gear revolves, pin D moves A around on 
C as a centre of motion. A is provided with a slot 
carrying a pin, X, on which is pivoted the rod, R. 
The motion of end N of the rod R being in a straight 
line, M, it is required to find the positions of N during 
twenty-four periods in one revolution of G. In Figure 
288 let H' represent the path of motion of the driving 




\ Fig. 287. 

pin D, about the centre of B, and H the path of mo- 
tion of X about the centre C ; these two centres cor- 
responding to the centres of B and C respectively, in 
Figure 287. Let the line M correspond to the line 
of motion M in Figure 286. Now since it is the pin 
D, Figure 287, that drives, and since its speed of rev- 
olution is uniform, we divide its circle of motion H' into 
tvv(Mny-four equal divisions, and by drawing lines- radi- 
ating from centre C,and passing through the lines of di- 



PLOTTING MECHANICAL MOTIONS. 



255 



vision on H' we get on circle H twenty- four positions for 
the pin X in Figure 286. Then setting the compasses 
to the length of the rod (R, Figure 286), we mark from 




i 



Fig. 288. 

position I on circle H as a centre line, a; from position 
2 on H we mark line b, and so on for the whole twenty- 
four positions on circle H, obtaining from a to n for the 



256 



MECHANICAL DRAWING SELF-TAUGHT. 



forward, and from n to y for the motion during the 
backward stroke. Suppose now that the mechanism 
remaining precisely the same as before, the line M of 
motion be in a line with the centres C, B, instead of at 




a right angle to it, as It is in Figure 286, and the motion 
under this new condition will be as in Figure 289; the 
process for fmding tlie amount of motion along M 
from the motion around H being precisely as before. 



PLOTTIXG MECHANICAL MOTIONS 



257 



In Figure 290 is shown a cutter-head for a wood 




Fig. 290. 

moulding machine, and it is required to find what 
17 



258 MECHANICAL DRAWING SELF-TAUGHT. 

shape the cutting edge of the cutter must be to form 
a mouldlnof such as is shown in the end view of the 
moulding in the figure. Now the line A A being at 
a riofht ano^le to the hne of motion of the mouldinor as 
it is passed beneath the revolving cutter, or, what is 
the same thinor, at a rioht anorle to the face of the 
table on which the moulding is moved, it is obvious 
that the highest point C of the moulding will be cut to 
shape by the point C of the cutter ; and that since the 
line of motion of the end of the cutter is the arc D, 
the lowest part of the cutter action upon the moulding 
will be at point E. It will also be obvious that as the 
cutter edge passes, at each point, its length across the 
line A A, it forms the moulding to shape, while all the 
cuttine action that occurs on either side of that line is 
serving simply to remove material. All that we have 
to consider, therefore, is the action on line A A. 

It may be observed also that the highest point C of 
the cutter edge must not be less than ^ inch from the 
corner of the cutter head, which gives room for the 
nut N (that holds the cutter to the head) to pass over 
the top of the moulding in a 2y2 inch head. In pro- 
portion as the heads are made larger, however, less 
clearance is necessary for the nut, as is shown in Figure 
291, the cutter ^d.^g^ extending to C, and therefore 
nearly up to the corner of the head. Its patli of mo- 
tion at C is shown by dotted arc B, which it will be 
observed amply clears the nut N. In practice, how- 
ever, point C Is not in any size of cutter-head placed 
nearer than y^ Inch from corner X of the cutter-head. 

To find the length of the cutter (kX^ki necessary to 
produce a glvcin de[)th of moulding, we may draw a 



PL O TI ING MECHANICAL MO flONS. 



259 



circle/, Figure 292, equal in diameter to the size Of 
the cutter head to be used, and line A A. The 
highest point of cutting edge being at e, and the 
lowest at ^, then circles d and/" represent the line of 
motion oi these two points; and if we mark the cutter 
in, the necessary length of cutting edge on the cutter 
is obviously from ^ to <^. 




Fig. 291. 

Now the necessary depth of cutter edge being found 
for any given moulding, or part of a moulding, the 
curves for the edge maybe found as follows: Sup- 
pose the moulding Is to be half round, as In the end 
view in Figure 290. The width of the cutter must 
of course equal the width of the moulding, and the 
length, or depth of cutting edge required may be 



26o 



MECHANICAL DRAWING SELF-TAUGHT. 



found from the construction shown in Figure 292; 
hence all that remains is to find the curve for the cuttincr 
edge. In Figure 293, let A A represent the centre 
of the cutter width, its sides being F F', and its end B B. 
From centre C draw circle D, the upper half of which 
will serve to represent the moulding. Mark on A the 
length or depth the cutting edge requires to be, ascer- 
taining the same from the construction shown in Figure 




292, and mark it as from C to K'. Then draw line 
E E, passing through point K. Draw line G, standing 
at the same angle to A A as the foce h b. Figure 292, 
of the cutter docs to the line A A, and draw line H 
H, parallel to G. From any point on G, as at I, with 
radius J, draw a quarter of a circle, as K. Mark off 
this quarter circle into ecjual points of division, as by 
I, 2, 3, e^., and from these points of division draw 



PLOTTING MECHANICAL MOTIONS, 
my 



261 




Fig. 293. 



L 



262 



MECHANICAL DRAWING SELF-TAUGHT, 



lineS; as ^, <^, r, etc. ; and from these lines draw hor- 
izontal lines d, c,/, etc. Now divide the lower half of 
circle D into twice as many e^ual divisions as quarter 
circle K is divided into, and from these points of di- 
vision draw perpendiculars g, h, i, etc. And where 
these perpendiculars cross the horizontal lines, as d, 
will be points through which the curvv^ maybe drawn, 
three of such points being marked by dots at p, q, r. 




Molding 

Fig. 294. 

If the student will, after having drawn the cur\'e by 
this construction, draw It by the construction that was 
explained in connection with Figure 79, he will hnd 
the two methods give so nearly identical curves, that 
tlie latter and more simple method may be usetl 
without senslbh.' error. 

When the curves o{ tlie mouKlI ng are not arcs of 
circles they may be marked as follows: 



PL O TTIXG MECHA XICA L MO T/U. \ '.V. 



-yf* 



'^3 



Take the drawincr of the mouldinir and divide each 
member or step of it by equidistant Hnes, as a, b,c, d, e, 
f,g, in Figure 294; above the moulding draw lines 
representing the cutter, and having found the depth 
of cutting ^(^^^ for each member by the construction 
shown in F"igure 292. finding a separate line, a b, for 
each member of the moulding, transfer the depths so 
found to the face of the cutter; divide the depth of 
each member of the cutter into as many equal divisions 
as the corresponding member of the moulding is 
divided into, as by lines //, /', 7', k, /, m, n. Then draw 
vertical lines, as o, p, g, r, etc.; and where these lines 
meet the respective lines //, /, /. etc., are points in the 
curve, such points being marked on the cutter by dots. 



CHAPTER XIII. 

EXAMPLES IN LINE- SHADING AND DRAWINGS FOR 
LINE-SHADED ENGRAVINGS. 

Although in workshop drawings, line-shading is 
rarely employed, yet where a design rather than the 
particular details of construction is to be shown, line- 
shading is a valuable accessory. Figure 295, for 
example, is intended to show an arrangement of 
idle pulleys to guide belts from one pulley to another; 
the principle being that so long as the belt passes to 
a pulley moving in line with the line of rotation of 
the pulley, the belt will run correctly, although it may 
leave the pulley at considerable angle. When a belt 
envelops two pulleys that are at a right angle to each 
other, two guide pulleys are needed in order that the 
belt may, in passing to each pulley, move in the same 
plane as the pulley rotates in, and the belt is in this case 
given what is termed a quarter twist. 

It will be observed that by the line-shading even 
the twist of the belt is much more clearly shown than 
it would be if left unshaded. 

An excellent example of shading is given in Figure 
296, which is extractc^l from the Anicrican Macliiiiist, 
and represents a cutting tool for a planing machine. 
The figure is from a wood engraving, but the cHect 
may be prodncc^d by liners, the black i)arts being con- 
siderc'd as simply broad black lines. 
(264) 



EXAMPLES IN LINE-SHADING. 




Fig- 295- 



266 



MECHANICAL DRAWING SELF-TAUGHT. 



The dravvlnos from which encrravino^s are made are 
drawn to conform to the process by which the engrav- 
iiig is to be produced. Drawings that are shaded by 
plain lines maybe engraved by three methods. First, 
the drawing may be photo-engraved, in which process 
the drawing is photographed on the metal, and every 




Fig. 296. 

line appears in the engraving precisely as it appears 
in the drawing. 

For this kind of engraving die drawing may be 
made of any convenient size that is larger than the 
size of engraving to be produced, the reduction of size 
l)eing produced in the photographing process. Draw- 
ings for photo-engraving require to Iiave the lines jet 



EXAMPLES hX LINE-SHADIXG. 267 

black, and it is to be remembered that if red centre- 
lines are marked on the drawing, they will be produced 
as ordinary black lines in the engraving. 

The shading on a drawing to be photo-engraved must 
be produced by lines, and not by tints, for tints, whether 
of black or of colors, will not photo-engrave properly. 

It is generally preferred to make the drawing for a 
photo-engraving larger than the engraving that is to 
be made from it, a good proportion being to make 
the drawing twice the length the engraving is to be. 
This serv-es to reduce the magnitude of any rough- 
ness in the lines of the drawing, and, therefore, to 
make the engraving better than the drawing. 

The thickness of the lines in the drawine should be 
made to suit the amount of reduction to be made, be- 
cause the lines are reduced in thickness in the same 
proportion as the engraving is reduced from the 
drawine. Thus the lines on an enorravine reduced to 
one-half the dimensions of the drawing would be 
one-half as thick as the lines on the drawing. 

Drawings for photo-engraving should be made on 
smooth-faced paper; as, for example, on Bristol board; 
and to make the lines clean and clear, the drawing in- 
struments should be in the best of condition, and the 
paper or Bristol board quite dry. The India rubber 
should be used as litde as possible on drawings to be 
photo-engraved, because, if used before the lines are 
inked in, it roughens the surface of the paper, and the 
inkinor lines will be less smooth and even at their 
edo-es; and for this reason it is better not to rub out 
any lines undl all the lines have been inked in. If used 
to excess after the lines have been inked in it serves 



268 MECHANICAL DRAWING SELF-TAUGHT. 

to reduce the blackness of the lines, and may so pale 
them that they will not properly photo-engrave. 

To make a drawing for an engraver in wood it would 
be drawn directly on the face of the box-wood block, 
on which it is to be engraved. The surface of the block 
is first whitened by a white water color, as Chinese 
white. If the drawing that is to be used as a copy is 
on sufficiently thin paper, its outline may be traced 
over by pencil lines, and the copy may then be laid 
face down on the wood block and its edgres held to the 
block by wax, the pencilled lines being face to the 
block. The outline may then be again traced over 
wath a pencil or pointed instrument, causing the im- 
print of the lead pencil lines to be left on the whitened 
surface of the block. If the copy is on paper too 
thick to be thus employed, a tracing may be made and 
used as above ; it being borne in mind that the tracing 
must be laid with the pencilled lines on the block, be- 
cause what is the riorht hand of the drawing on the 
block is the left hand in the print it gives. The 
shading on wood blocks is given by tints of India ink 
aided by pencilled lines, or of course pencilled lines 
only may for less artistic work be used. Another 
method is to photograph the drawing direct upon the 
surface of the wood block ; it is unnecessary, however, 
to enter into this part of the subject. 

The third method of producing an engraving from 
a drawing is by means of what is known as the wax 
process. Drawings for this process should be made 
on thin paper, for the following reasons : The process 
consists, briefly slated, in coating a copper plate with 
a layer of wax about Va inch deep, and in drawing 



EXAMPLES IN LINE-SHADING. 269 

upon the wax the lines to compose the engraving, 
which Hnes are produced by means of tools that re- 
move the wax down to the surface of the copper. 

The plate and wax are then placed in a battery and 
a deposit of copper fills in the lines and surface of 
the wax, thus forming the engraving. Now if the 
drawing is made on thin paper, the engraver coats the 
surface of the drawing with a dry red pigment, and 
with a pointed instrument traces over the lines of the 
drawing, which causes them to leave a red imprint on 
the surface of the wax, and after the drawing is re- 
moved the engraver cuts these imprinted lines in the 
wax. If the drawing is on thick paper, this method 
of transferrino- the drav/inor to the wax cannot be used, 
and the engraver may take a tracing from the drawing 
and transfer from the tracinor to the wax. It is obvi- 
ous, also, that for wax engravings the drawing should 
be made of the same size that the engraving is required 
to be, or otherwise the tracing process described cannot 
be used. Figure 297 represents an engraving made 
by the wax process from a print from a wood engrav- 
ing, and it is obvious that since all the lines drawn on 
the wax sink down to the surface of the copper plate, 
the shading is virtually composed of lines, the black 
surfaces being where the lines have been sufficiently 
close toeether and broad to remove all the wax en- 
closed within those surfaces. 

The wax process is, however, more suitable for en- 
gravings in plain outline only, and is especially excel- 
lent when the parts are small and the lines fall close 
together; as, for example, in Figures 298 and 299, 
which are engravings of a boiler drilling machine, and 



MECHANICAL DRAWING SELF-TAUGHT. 




Fig. 297. 



EXAMPLES IX LINE-SIIADIXG. o?! 




Fig. 298. 



2/2 



MECHANICAL DRAWING SELF-TAUGHT, 



were produced for the American Machinist by tracing 
over a wood eno^ravinof from London, " Enoflneerlne " 
in the manner already described. The fineness and 
cleanness of the lines in the wax process is here well 
illustrated, the disposition of the parts being easily 
seen from the engraving, and easily followed in con- 
nection with the following description : 

The machine consists of two horizontal bed-plates 
A I and A 2, made with Y slides on top, and placed 
at right angles to each other. Upon each of the bed- 
plates is fitted a vertical arm B i and B 2, each of 
which carries two saddles, C i and C 2, these being each 
adjustable vertically on its respective arm by means 
of rack and pinion and hand wheels D i and D 2.. 
The saddles are balanced so that the least possible 
exertion is sufficient to adjust them. The vertical 
arms, B i and B 2, are cast each with a round foot by 
which the arms are attached to the square boxes E i 
and E 2, which are fitted to the Y slides on the hori- 
zontal beds A I and A 2, and are adjustable thereon 
by means of screw and ratchet motion F i and F 2. 
Each of the square boxes has cast on it a small arm 
G I and G 2, carrying studs upon which run pinions 
oearincr into the circular racks at the foot of the ver- 
tical arms. The square boxes have each a circular 
groove turned in the top to receive the bolts by which 
the vertical arms are connected to them, and thus the 
vet-tical arms, and with them the drill spindles N i and 
N 2, are adjustable radially with the boiler — the adjust- 
ment being effixted i)y means of the pinions and cir- 
cular racks. Tiie pinions are arranged so that they 
can b(^ worked with the same screw key that is used 
for the bolts in the circular <rrooves. 



EXAMPLES IN LINE-SIIADIXG. 



273 



The shell to be drilled is placed upon die circidar 
table H, which is carried by suitable framework ad- 
justable by means of screw on a V slide I, placed 
at an angle of 45° with the horizontal bed-plates. By 
this arranorement. when the table is moved alonor I, it 
will approach to or recede from all the drills equally. 
J I and J 2 are girders forming additional bearings for 
the framework of the table. The bed-plates and slides 
for the table are bolted and braced tOL^ether, makinor 
the whole machine very firm and rigid. Power is ap- 
plied to the machine through the cones K i and K 2, 
working the horizontal and vertical shafts L i and L 2, 
etc. On the vertical shafts are fitted coarse pitch 
worms sliding on feather keys, and carried with the- 
saddles C i and C 2, etc. The worms gearing with the 
worm wheels M i and M 2 are fitted on the sleeves 
of the steel spindles Ni and N2. The spindles are 
fitted with self-acting motions O i and O2, which are 
easily thrown in and out of gear. 

The machine is also used for turning the edee of. 
the flanges which some makers prefer to have on the 
end plates of marine boilers. The plates are very 
readily fixed to the circular table H, and the edge of 
the flange trued up much quicker than by the ordinary 
means of chipping. When the machine is used for 
this purpose, the cross beam P, which is removable, is 
fastened to the two upright brackets Ri and R2. 
The cross beam is cast with V slides at one side for a 
little more than half its length from one end, and on 
the opposite side for the same length, but from the 
opposite end. The V slides are each fitted with a 
tool box Si and S2, having a screw adjustment for 
18 



2^4 MECHANICAL DRAWING SELF-TAUGHT. 

setting- the tool to the depth of cut, and adjustable on 
the V slides of the cross beam to the diameter of the 
plate to be turned. This arrangement of the machine 
is also used for cutting out the furnace mouths in the 
boiler ends. The plate is fastened to the circular table, 
the centre of the hole to be cut out being placed 
over the centre of table; one or both of the tool boxes 
may be used. There is sufficient space between the 
upright brackets Ri and R2, to allow that section of 
a boiler end which contains the furnace mouths to re- 
volve, while the holes are being cut out; the plate be- 
lonorine to the end of a boiler of the largest diameter 
that tlie machine will take in for drilling. The holes 
cut out will be from 2 feet 3 inches in diameter and 
upwards. Power for using the turntable is applied 
through the cone T. The bevel wheels, worms, worm 
wheels, and pinions for driving the tables are of cast 
steel, which is necessary for the rough work of turning 
the flancres. 

As to the practical results of using the machine, the 
drills are driven at a speed of 340 feet per minute at 
the cutting edges. A jet of soapsuds plays on each 
drill from an orifice ^2 in. in diameter, and at a pressure 
of 60 lbs. per square inch. A joint composed of two 
I -inch plates, and having holes i and one-eighth in. 
in diameter, can be drilled in about 2^ minutes, and 
allowing about half a minute for adjusting the drill, 
each drill will do about 20 holes j:)er hour. The 
machine is clesigntxl to stand any amount of work 
that the drills will ])ear. The time required for putting 
on the end of a boihu* and turning the flange thereon 
(say 14 feet diameter) is about 2^< hours; much, 



* 




' ^^-^-^ ?- 2 . 4 „ C 



J - I —1 I. 



Fig. 2^ 




°age 275.) 






( 






EXAMPLES EV LEXE-SHADEXG. 275 

however, depends on die state of the flanges^ as some- 
times they are very rough, while at others very Httle 
is necessary to true them up. The time required for 
putting on the plate containing the furnace mouths 
and cutting out three holes 2 feet 6 in. in diameter, 
the plate being i and one-eighth in. thick, is three 
hours. Of course, if several boilers of one size are 
beine made at the same time, the holes in two or 
more of these plates can be cut out at once. The 
machine is of such design that It can be placed with 
one of the horizontal bed-plates (say A ij. parallel 
and close up to a wall of the boiler shop; and when 
the turning apparatus is being used, the vertical arm 
B»2 can be swiveled half way round on its square box 
E 2, and used for drilling and tapping the stay holes 
In marine boiler ends after they are put together; of 
course sufficient room must be left between bed-plate 
A 2, and the wall of boiler shop parallel with It, 
to allow for reception of the boiler to be operated 
upon. 

It would obviously be quite difficult to draw such 
drawings as In Figures 298 and 299 on thin paper, so as 
to enable the drawl nor to be traced on the wax direct 
by the process before described, unless Indeed the 
draftsman had considerable experience in fine work; 
hence, it is not uncommon to make the drawlncr laree, 
and on ordinary drawing paper. The engraver then 
has the drawing photographed on the surface of the 
wax, and works to the photograph. The letters of 
reference in wax engravings are put in by impressing 
type in the wax, and In this connection It may be re- 
marked that the letters I and O should not be used on 



2^6 MECHANICAL DRAWING SELF-TAUGHT, 

drawings to be engraved by the wax process, unless 
they are situated outside the outlines of the drawing, 
because the I looks so much like part of a dotted line 
that it is often indistinguishable therefrom, while the 
O looks like a circle or an ellipse. 



CHAPTER XIV. 
SHADING AND COLORING DRAWINGS, 

The shading or coloring of drawings by tints is 
more employed in large drawings than in small ones, 
and in Europe than in the United States ; while on t],ie 
other hand tinting by means of line-shading is more 
employed in the United States than in Europe, and 
more on small drawinors than on laro-c ones. 

Many draftsmen adopt the plan of coloring the 
journals of shafts, etc., with a light tint, giving them 
the deepest tint at the circumference to give them a 
cylindrical appearance. This makes the drawing 
much clearer and takes but little time to do, and is 
especially advantageous where the parts are small or 
on a small scale, so that the lines are comparatively 
close together. 

For simple shading purposes black tints of various 
degrees of darkness may be employed, but it is usual 
to tint brass work with yellow. Cast iron with India 
ink, wrought iron with Prussian blue, steel with as light 
purple tint produced by mixing India ink, Prussian 
blue and a tinge of crimson lake. Copper is tinted 
red. On plane surfaces an even tint of color is laid, 
but if the surfaces are cylindrical they are usually 
colored deeper at and near the circumference, and are 

(277) 



278 MECHANICAL DRAWING SELF-TAUGHT, 

tinted over the colors with light tints of India ink to 
show their cylindrical form. 

If a drawing is to be colored or shaded with India ink 
the paper should be glued all around its edges to the 
drawing board, and then dampened evenly all over 
with a sponge, which will cause the paper to shrink 
and lay close to the surface of the drawing board. If, 
in applying a cojor or a tint, the -color dries before the 
w^hole surface is colored, the color will not be of an- 
equal shade; hence it is necessary before applying the 
color to dampen the surface, if it is a large one, so that 
the color at one part shall not get dry before there 
has been time to eo over the whole surface; a more 
even depth of color is attained by the application of 
several coats of a light tint, than with one coat, giving 
the full depth of color. But if the paper is not allowed 
to dry sufficiently between the coats, or if it has been 
made too wet previous to the application of the colors, 
it will run in places, leaving other hollow^s into which 
the color will How, making darker-colored spots. To 
avoid this the paper may be dried somewhat by the 
application of clean blotting paper. 

To maintain an even shade of color, it is necessary 
to slightly stir up the color each time the brush is 
dipped into the color saucer or palette, especially when 
the coloring is composed of mixed colors, because the 
coloring matter is apt to separate from the water and 
sink to the bottom. 

So, also, in mixing colors it is best to apply tlu^ end 
of the color to the surface of the palette and not to 
apply the brush direct to the cake of color, because 
the color is more completely mixed by contact with 



I 



SHADING AXD COLOR IXG DRAWIXGS. O/Q 

the palette than it can be by the brush, which may 
retain a speck of color that will, unless washed out, 
make a streak upon the drawing. 

To graduate the depth of tint for a c)-lindrical sur- 
face, it is best to mix several, as, say three depths or 
degrees of tint, and to first use the darkest, applying 
it in the direction \n which the piece is to be shaded 
darkest. The width this dark application should be is 
obviously determined by the diameter of the piece. 
The next operation is to lighten or draw the part, line 
or streak thus dark colored, causing it to get paler 
and paler as it approaches the axial line of the piece 
or cylinder. This lightening is accomplished as fol- 
lows : The dark streak is applied along such a length 
of the piece that it will not dry before there has been 
time to draw it out or lighten it on the side towards 
the axis. A separate brush may then be wetted and 

■ drawn alono- the edore of the dark streak in short 

strokes, causing the color to run outwards and become 

\ lighter as it approaches the axis. It will be found that 

during this process the brush will occasionally require 
washing in water, because from continuous contact 
with the dark streak tlie tint it contains will darken; 
When the first coat has been laid and spread or drawn 
out from end to end of the piece, the process may be 
repeated two or three times, the most even results 
being obtained by making the first dark streak not too 
dark, and croinof over the drawincr several times, but 
allowing the paper to get very nearly dry between 

Ieach coat. In small cylindrical bodies, as, say ^ inch 
in diameter, the darkest line of shadow may be located 
at the Hnes representing the diameter of the piece, but 






28o MECHANICAL DRAWING SELF-TAUGHT. 

in pieces of larger diameter the darkest line may be 
located at a short distance from the line that denotes 
the diameter or perimeter on the shadow or right-hand 
side of the piece, as is shown in many of the engravings 
that follow. It is obvious that if a drawing is to have 
dimensions marked on it, the coloring or tindng should 
not be deep enough to make it difficult to see the di- 
mension figures. 

The size of the brush to be used depends, of course, 
upon the size of the piece to be shaded or colored, and 
it is best to keep one brush for the dark tint and to 
never let the brush drv with the tint in it, as this 
makes it harsh. In a o^ood brush the hairs are fine, 
lie close together when moistened, are smooth and 
yet sufficiently stiff or elastic to bend back slightly 
when the pressure is removed. If, when under pres- 
sure and nearly dry, the hairs will separate or the 
brush has no elasticity in it, good results cannot be 
obtained. All brushes should be well dried after use. 

The light in shading is supposed to come in at the 
left-hand corner of the drawing, as was explained with 
reference to the shade line. 

Excellent examples to copy and shade with the 
brush are oiven as follows : 

Figure 300 represents a Medart pulley, constructed 
by the Hartford Steam Engineering Company ; the 
arms and hub are cast in one piece, and the rim is a 
wrought iron l)and riveted to the arms, whose ends 
are turnc^l or ground tru(^ widi the^ hub bore. The 
figure is obviously a wood engraving, but it presents 
the varying degrees of shade or shadow with sufficient 
accuracy to form a good example to copy and brush 



SI/ADIXG AXD COLORING DRAWINGS. 



281 



shade with India ink. Figure 301 represents a similar 
pulley with a double set of arms, forming an excellent 
example in perspective drawing, as well as for brush- 



shadino-. 



In brush-shading as with line-shading, the difficulties 
Increase with an increase in the size of the piece, and 
the learner will find that after he has succeeded toler- 
ably well in shading these small pulleys. It will be quite 




Fig. 300. 
difficult, but excellent practice to shade the large pulley 



in Figure 302. 



One of the principal considerations is to not let the 
color dry at the edges in one part while continuing 
the shading In another part of the same surface, hence 
it is best to begin at the edge or outline of the draw- 
ing and carry the work forward as quickly as possible, 



282 



MECHANICAL DRAWING SELF-TAUGHT. 



occasionally slightly wetting with water edges that 
require to be left while the shading is proceeding in 
another direction. 

When it is required to show by the shading that tl)e 
surfaces are highly polished, the lighter parts of the 
shading are made to contain what may be termed 
splashes of lighter and darker shadow, as in Figure 
3,03, which represents an oil cup, having a brass casing 




Fig. 30 I: 

enclosing a glass cylinder, which appears through the 
openings in the brass shell. 

Figure 304 represents an iron planing machine 
whose lin(.'-shadiiio- is so evenly effected that it aftbrds 
an excc^llcnt exain|)l{^ of shading. Its parts are similar 
to those siiown in the iron planer in I^gure 297, save 
that it rarri(\s two slichiig heads, so as to enable the 
use, sinuiltant!Ouslv, of two cutting- tools. 




1^'- ^o. 




iPage 282.) 



SHADING AND COLORING DRAWINGS. 



283 



I 




Fig. 302. 



284 



MECHANICAL DRAWING SELF-7'AUGBT. 



A superior example in shadingr is shown in Figures 
305 and 306, which represent a plan and a sectional 
view of the steam-cylinder of a Blake's patent direct- 
acting steam-pump. The construction of the parts is 
as follows : A is the steam-piston ; H i and H are the 




Fig. 303- 
cylinder steam-passages ; M is the cylinder exhaust 
port. 

The main valve, whose movement alternately opens 
the ports for the admission of steam to, and the escape 
of steam from, the main c)hnder, is divided into two 






SHADING AND COLORING DRAWINGS. 




285 



Fig. 305. 



286 MECHANICAL DRAWING SELF-TAUGHT. 

parts, one of which, C, sHdes upon a seat on the main 
cylinder, and at the same time affords a seat for the 
other part, D, which sHdes upon the upper face of C. 
As shown in the eneravincrs, D is at the left-hand end 
of Its stroke, and C at the opposite or right-hand end 
of its stroke. Steam from the steam-chest, J, is there- 
fore entering the right-hand end of tlie main cylinder 
through the ports E and H, and the exhaust is escap- \ 

Ing through the ports H i, E i, K and M, which causes » 

the main piston A to move from right to left. When ; 

this piston has nearly reached the left-hand end of its 
cylinder, the tappet arm, T, attached to the piston-rod, 
conies In contact with, and moves the valve rod collar 
O I and valve rod P, and thus causes C, together with 
tlie supplemental valves R and S S i, which form, with 
C, one casting, to be moved from right to left. This 
movement causes steam to be admitted to the left-hand 
end of the supplemental cylinder, whereby its piston B 
^vIU be forced towards the right, carrying D to the op- 
posite or right-hand end of its stroke ; for the move- 
ment of S closes N (the steam-port leading to the 
right-hand end), and the movement of S i opens N i 
(the steam-port leading to the opposite or left-hand 
end), at the same time the movement of V opens the 
right-hand end of this cylinder to the exhaust, through 
the exhaust ports X and Z. The parts C and D now 
have positions opposite to those sliown in the engrav- 
ings, and steam is therefore entering the main cylinder 
through the ports 1^ i and II i,and escaping througli 
the ports H, \\, K and M, which causes the main pistoti 
A to move in the opposite direction, or from left to 
right, and oi)(!rations similar lo those already described 



SHADING AND COLORING DRAWINGS, 



287 




Fig. 306. 



288 MECHANICAL DRAWING SELF-TAUGHT. 

will follow, when the piston approaches the right-hand 
end of its cylinder. By this simple arrangement the 
pump is rendered positive in its action ; that is, it wdll 
instantly start and continue working the moment steam 
is admitted to the steam-chest, while at the same time 
the piston is enabled to move as slowly as the nature 
of the duty may require. It will be noted that in Figure 
305, the ports of C are shown through D, whose loca- 
tion is marked by dark shading. This obviously is 
not correct, because D beino; above C should be 
shaded lighter than C, and again the ports E i and K 
could not show dark through the port D. They might, 
of course, be shown by dotted outlines, but they would 
not appear to such advantage, and on this account it 
is permissible where artistic effect is sought, the object 
being to subserve the shading to making the mech- 
anism and Its operation clearly and readily understood. 
Figure 307 affords another excellent example for 
shading. It consists of an Independent condenser, 
w^hose steam-cylinder and valve mechanism is the 
same as that described with reference to Figures 305 
and 306. 




F'g- 307- (h 




^288.) 




New Automatic High Speed 

ROLLING MILL ENGINE. 

Cylinder 12x26'. 




jn 



r. 



i 



Fig. ^oR. (Page 289.) 




Fig. 309. (Page 289.) 



I 



mm m m, j Ti^^r 




Fig. 310 — Sf:( ru^N np- C'vi.ini>kr and Sikam (^m:sf. (Page 2^9.) 



A 



CHAPTER XV. 

EXAMPLES IN ENGINE WORK, 

In the figures from 308 to 328 inclusive are given 
three examples in engine work, all these drawings 
being from The American Machi7iist. Figures 308 to 
314 represent drawings of an automatic high speed 
engine designed and made by Professor John E. and 
William A. Sweet, of Syracuse, New York. Figure 
308 is a side and 309 an end view of the engine. 
Upon a bed-plate is bolted two straight frames, be- 
tween which, at their upper ends, the cylinder is se- 
cured by bolts. The guides for the cross-head are 
bolted to the frame, which enables them to be readily 
removed to be replaned when necessary. The hand 
wheel and rod to the right are to operate the stop- 
cock for turninof on and off the steam to the steam- 
chest. 

The objects of the design are as follows : Figure 
310 is a vertical section of the cylinder through the 
valve face, also showing the valve in section, and it 
wall be seen that the lower steam passage' enters the 
cylinder its full depth below the inside bottomi, and 
that the whole inside bottom surface of the cylinder 
slopes or inclines towards the entrance of this passage. 
The object of this is to overcome the difficulty expe- 
rienced from the accumulation of w^ater in the cylinder, 
19 (289) 



2cp MECHANICAL DRAWING SELF-TAUGHT. 

which, in the vertical engine, is usually a source of 
considerable annoyance and frequently the cause of 
accident. 

Any water that may be present in the bottom finds 
its way by gravity to the port steam entrance, and is 
forced out by and with the exhaust steam at or before 
the commencement of the return stroke. 

To assist in the escape of water from the top of the 
cylinder, the piston is made quite crowning at that 
end, the effect of which Is to collect the water in a 
narrow band, instead of spreading It over a large sur- 
face. This materially assists in its escape, and at the 
same* time presents a large surface for the distribution 
of any water that may not find its way out in advance 
of the piston. 

The piston Is a single casting unusually long and 
light, and is packed with four spring rings of \ inch 
square brass wire. 

The valve Is a simple rectangular plate, working 
between the valve face and a cover plate, the cover 
plate being held In its proper position, relative to the 
back of the valve, by steam pressure against Its outer 
surface, and by resting against loose distance pieces 
between its inner surface and tlie valve seat. This 
construction admits of the valve leaving the seat, if 
necessary, to relieve the cylinder from water, as in the 
instance of priming, and also, by tlie reduction of these 
pieces, admits of ready adjustment to contact, should 
it become necessary. 

The cover plate is provided with recesses on its 
inner surface whicli exactly correspond with the ports 
in the valve face, and the corresponding ports and re- 



EXAMPLES IN ENGINE WORK. 



291 




Fig. 311 — Valve Motion. 



292 MECHANICAL DRAWING SELF-TAUGHT. 

cesses are kept in communication with each other by 
means of relief passages in the valve. From this it 
will be seeil that the valve is subjected to equal and 
balanced pressure on each of its sides, and hence, is in 
equilibrium. 

The valve is operated through the valve motion, 
shown in Figure 311, the eccentric rod of which hooks 
on a slightly tapered block that turns on the pin of the 
rock arm, like an ordinary journal box. 

The expansion, or cut-off, Is automatically regulated 
•by the operation of the governor In swinging the 
slotted eccentric In a manner substantially equivalent 
to moving it across the shaft, but Is however favorably 
modified by the arrangement of the rock arm, which, 
in combination with the other motions, neutralizes the 
unfavorable operation of the usual shifting eccentric, 
and which, in connection with the large double port 
opening, provides for a good .use of steam from o to 
Y^ stroke. 

The governor shown in Figure 312 is of the disc 
and single ball type, the centrifugal force of the ball 
being counteracted by a powerful spring. Friction is 
reduced to a minimum in the governor connection, by 
introducing steel rollers and hardened steel plates in 
such a manner as to provide rolling instead of sliding 
motion. 

In order that a governor shall correctly perform its 
functions, It is unquestionably necessary that it have 
power largely in excess of the work requir'^d of it, and 
also that the friction shall represent a very low per- 
centage of that power. In respect to this, especial 
means have been employed to reduce the friction ; the 



Jl 



EXAMPLES IX EXGINE WORK. 



^93 



valve being balanced, requires but little power to move 
it, while the governor ball being made heavy for the 
purpose of counterbalancing the weight of the eccen- 
tric and strap, its centrifugal force when the engine is 




Fig. 312 — Governor. 

at full speed is enormous, the spring to counteract it 
having to sustain from two to three thoztsand pounds. 
Under these circumstances, as might be expected, the 
regulation is remarkably good. This is a very impor- 



^94 



MECHANICAL DRAWING SELF- 7 AUGHT. 



tant consideration in an engine working under the 
conditions of a roll-train engine. 

Figure 313 represents a section of the pillow block 
box, crank-pin and wheel, together with the main 
journal. It will be seen that the end of the box next 




Fig. 313 — Section of Pillow Block. 

tlie crank wheel has a circular oroove around its out- 
side, and that a corresponding groove in the crank 
wiicel proj(!cts over this groove. I'^rom this latter 
groove an oil hok^ of liberal size extends, as shown, to 
tlu! surface of the crank-pin. Any oil placed at the 
upper [jart of the groove on the box finds its wa\ by 




J'K- 314— ^^^'oNNiXTiNi: Rod. (Page 295.) 



EXAMPLES IX ENGINE WORK. ' 295 

gravity Into the groove In the crank wheel, and Is car- 
ried by centrifugal force to the outside surface of the 
crank-pin ; so that whatever other means of lubrication 
may be employed, this one will always be positive in 
its action. This cut also shows the manner in which 
the box overlaps the main journal and forms the oil 
reservoir. 

Another feature In the construction of this box 13 
the means by which It is made to adjust itself in line 
with the shaft. It will be observed that it rests on the 
bottom of the jaws of the frame on two inclined sur- 
faces, which form equal angles with the axis of the 
shaft when In Its normal position, and that by 
moving longitudinally in either direction, as may be 
necessary, the box will accommodate Itself to a change 
in the alignment of the shaft. In order that It may be 
free to move for this purpose it is not fitted with the 
usual fore and aft flanges. By this means any slight 
derafiorement, as in either the outboard or inboard 
bearino- wearing down the fastest, is taken care of, the 
movement of the box on the inclined surfaces beine 
for this purpose equivalent to the operation of a ball 
and socket bearing. 

Figure 314 gives a side and an edge view of the 
connecting rod, the rod belncr in section in the edee 
view, and the brasses In section lined In both views. 

The cross-head pin, it will be observed, is tapered, 
and Is drawn home in the cross-head by a bolt ; the 
sides of the pin are flattened somewhat where the 
journal is, so that the pin may not wear oval, as it Is 
apt to do, because of the pull and thrust strain of the 
rod brasses falling mainly upon the top and bottom of 



2^6 MECHANICAL DRAWING SELF-TAUGHT. 

the journal, where the most wear therefore takes 
place. The brasses at the crossed end are set up by 
a wedge adjustable by means of the screw bolts 
shown. The cross-head wrist pin being removable 
from the cross-head enables the upper end of the rod 
to have a solid end, since it can be passed into place 
in the crossed and the wrist pin inserted through the 
two. The lower ends of the connecting-rod and the 
crank-pin possess a peculiar feature, inasmuch as by 
enlarging the diameter of the crank-pin, the ends of 
the brasses overlap, to a certain extent, the ends of 
the journal, thus holding the oil and affording increased 
lubrication. The segments that partly envelop the 
cross-head pin and crank-pin, and are section lined in 
two directions, producing crossing section lines, cr 
small squares, show that the brasses are lined with 
babbitt metal, which is represented by this kind of 
cross-hatching. These drawings are sufficiently open 
and clear to form very good examples to copy and to 
trace on tracing paper. 

Figures 315, 316 and 317 represent, in place upon 
its setting, a 200 horse-power horizontal steam-boiler 
for a stationary engine, and are the design of William 
H. Hoffman. The cross-sectional view of the boiler- 
shell in Figure 315 shows the arrangement of the 
tubes, which, having clear or unobstructed passages 
between the vertical rows of tubes, permits the steam 
to rise freely and assists the circulation of the water. 
The dry pipe (which is also shown in Figure 316) is a 
perforated pipe tlirougli which the steam passes to the 
engine cylinder, its objc!Ct being to carry off the steam 
as dry as possible ; thai is to say, without its carrying 



I 



/ 



1 




Side Sectional 

Fig. 316. 



il 



) 



L\ 



EXAMPLES IN ENGINE WORK. 



297 



away with the steam any entrained water that may be 
held in suspension. Figure 316 is a side elevation 
with the setting shown in section, and Figure 317 is 
an end view of the boiler and settino- at the furnace 

o 

end. The boiler is supported on each^ide by channel 




©OOOO: 

■Q-O-Q-Q-O- 



H 




00000 
00000 

0000 
00© 




Scale 



'A. 



Fig 



Ifoot. 
315- 



iron columns, these being riveted to the boiler shell 
angle pieces which rest upon the columns. The heat 
and products of combustion pass from the furnace 
along the bottom of the boiler, and at the end pass into 



2q8 mechanical drawing SELF-TAUGHT. 

and through the tubes an4 thence over the top of the 
boiler to the chimney flue. There is shown in the 




IProiit Elevation 
Fig. 317. 

bridc^c wall an opening;-, and its service is to admit air 
to the gases after they have passed the britlge wall, and 
thus complete the combustion of such gases as may 




Bessemer Steel Bars 



B 



7 n ^ 



10-4 



Fig. 



"5 — r 

1-4 I 

h- 

















~f 










i? 

? 




iO 





















^%- 



o 



Flan 



rn 



Pation 
age 299.) 




Elevation 

Fig. 318- (l^age 299.) 




VVoRKixo DRAWiXGi OF loo H. p. Steam 



EXC1^■E— Eo-ENTRIC A.SU tcCENTRHJ STRAP— Slall f=l tool. il'^ge 3«>'- 



- 




Fig. 319 — Cross vSkction of "Bed Platf near Junction witfi 



H 



^eam Pipe 

5"Diam. 




Fig. 321 — 100 II, P. Horizontal SrEAM-ENr.iNE— ELKVAtj 




Cylinder — Scale i^"=i Foot. (Page 299.) 



I 



r 




Fig. 322 — looM. P. Horizontal Steam-Enc 




5 D View of Cylinder — Scale ij4"—i Foot. 

) 



EXAMPLES IN ENGIiYE WORK. 299 

have remained unconsumed In the furnace. The 
cleansinor door at one end and that Hned with asbestos 
at the other, are to admit the passage of the tube 
cleaners. The asbestos at the top of the boiler shell 
is to protect it from any undue rise in temperature, 
steam being a poorer conductor of heat than water, 
and it beinor obvious that if one side of the boiler is 
hotter than the other it expands more from the heat 
and becomes longer, causing the boiler to bend, which 
strains and weakens it. The sides of the setting are 
composed of a double row of brick walls with an air 
space of three inches between them, the object being 
to prevent as far as possible the radiation of heat 
from the walls. The brick-staves are simply stays to 
hold the brick w^ork together and prevent its cracking, 
as it is apt, in the absence of staying, to do. 

Figures from 318 to 330 are working drawings of a 
loo-horse engine, designed also by William H. 
Hoffman. 

Figure 318 represents a plan and a side view of the 
bed-plate with the main bearing and the guide bars in 
place. The cylinder is bolted at the stuffing box 
end to the bed-plate, and is supported at the outer end 
by an expansion link pivoted to the bed-plate. The 
main bearing is provided with a screw for adjusting 
the height of the bottom piece of the bearing, and 
thus taking up the wear. The guide bars are held to 
the bed in the middle as well as at each end. 

Figures 319 and 320 represent cross sections of the 
bed-plate. 

Figure 321 represents a side elevation of the 
cylinder, and Figure 322 an end view of the same, 



300 



MECHANICAL DRAWING SELF-TAUGHT. 



the expansion support being for the purpose of per- 
mitting the cylinder to expand and contract under 




t.---//S — ^ 



Fii 



variations of temperature without acting to bend the 
bcd-platc, while at the same time the cyHndcr is sup- 




I''^'- 3-3 1°0 ^^- 1^- I'^'NCINE OUTSIDK \'l 



i \ 



Scale 1><^ — 1 foot 




C Cylinder and Steam-Chest. (Page 301.) 



J 




Fig. 324 — Sectional View of Cylinder anp >> 



« 




^ScALE 1% Inches = i Foot. (Page 301.) 



k 




I'^'K- 3-5~^'' ^"^ <^>- Cin-.Mi Dkvice. (Page 301.) 




^ Centre line of 

^ Main Valve Slew 

^'' 

3Ioveinent 3 is 



of Cut-off Stems, 



fa 




Fig. 326— Working Dkawin'j oi< 100 II. P. Fncink— Detaiu 




Hook Rod 



Uain Valve Motion — Scale 3"=! Foot. (Page 301.) 



ITM 




:x 



t^^ 



7ZAxrmzT-T 



-v-rn—x 



I I 



I — r 



1 I 




No finish here. 




5 3 






Z '^: 7 



^ 





];i;^r. ^28 100 ir. r. HoKl/ONTAL STKAil 




IpiNE — Cross Head. (Page 301.) 



EXAMPLES IN ENGINE WORK. 



301 



ported at both ends. The cyHnder and cyhnder covers 
are jacketted with hve steam In the steam-spaces shown. 

A view of the steam-chest side of the cyHnder is 
given in Figure 323, and a horizontal cross section 
of the cyHnder, the steam-chest and the valves, is 
shown in Figure 324. The main valves are connected 
by a right and left hand screw, to enable their ad- 
justment, as are also the cut-off valves. 

Figures 325 and 326 show the cam wrist plate and 
the cut-off mechanism. The cam wTlst plate, w^hlch is 
of course vibrated by the eccentric rod, has an inclined 
groove, whose walls are protected from w^ear by steel 
shoes. In this groove is a steel roller upon a pin at- 
tached to the bell crank operating the main valve stem. 
The operation of the groove Is to accelerate the 
motion imparled from the eccentric to the valve at 
one part of the latter's travel, and retard It at another, 
the accelerated portion being during the opening of 
the port for steam admission, and during Its closure 
for cutting off, which enables the employment of a 
smaller steam-port than would otherwise be the case. 

The shaft for the cam plate Is carried in a bearing 
at one end, and fits in a socket at the other, the socket 
and bearing being upon a base plate that Is bolted to 
the bed-plate of the engine; a side view of the con- 
struction being shown in Figure 327. 

Figure 328 represents the cross-head, whose wrist 
pin Is let Into the cross-head cheeks, so that It may be 
removed to be turned up true. The clip Is to prevent 
the piston rod nut from loosening back of Itself. 

Figure 329 represents a side view; and Figure 329^ a 
section through the centre of the eccentric and strap. 



MECHANICAL DRAWING SELF-TAUGHT, 




Fig- 327 — Working Drawiiii^of 100 H. P. Stcam-Knginc. — 
Wrist Plate— .s" = x Foot. 




Fig. 330—100 H. P. Horizontal SteamEngine— Connecting Rod. CPagejoa.) 



^'tJ- 3-7"^Vc)rkin^^ DmwiiiL^ of loo H. P. Steam-Engine. 
Wrist IMato.— .V = i Foot. 



EXAMPLES IN ENGINE WORK. 30 



The eccentric is let into the strap and is provided with 
an eye to receive a circular nut by means of which 
the length of the eccentric rod may be adjusted, a 
hexagon nut being upon the other or outer end of the 
eye. 

Figure 330 shows the construction of the connect- 
ing rod, the brasses of which are adjustable to take 
up the wear and to maintain them to correct length, 
notwithstanding the wear, by means of a key on each 
side of each pair of brasses, the keys being set up by 
nuts and secured by check nuts. 






INDEX. 



Ames' lathe feed motion, drawing a 

part of, 208. 
Angle of three lines, one to the other, 
to find, 55, 56. 
of two lines, one to the other, to 
find, 54, 55, 56. 
Angles, acute and obtuse, 57. 
Arc of a circle, an, 50. 
Arcs, construction with four, 67, 68. 
Arcs for the teeth of wheels, to draw, 

205. 
Arrangement of different views, 94-1 11. 
Automatic high speed engine, drawings 

of, 289. 
Axis of a cylinder, 51. 
of an ellipse, 63. 

Ball or sphere, representation of by line- 
shading, 87, 88. 
lied- plate, cros> section of, 299. 

plan and side view of, with main 
bearing and guide bars, 299. 
Bell-mouthed body, representation of 

by line-shading, 88, 89. 
Bevelled gear, one-half of, and an edge 
view projected from the same, 
207. 
one of which is line-shaded, 210. 
wheels, 203. 
Bevelled gears, small, 208. 
Bevelled wheels, a pair of, in section, 

208. 
Bisected line, 50. 

Black lines of a drawing, how to pro- 
duce, 32. 
Blacksmith, drawings for the, 172. 
Blake's patent direct acting steam 
pump, 284, 285. 
(20) 



Boiler drilling machine, a, 269, 270. 
Boiler, end view of, 297, 

shell, sectional view of, 296. 
Bolt heads and nuts. United States 
standard, 114, 118. 
I to draw a square-headed, 125. 

I with a hexagon head, to draw, 

113, 114. 
with a square under the head, 149. 
Bolts and nuts, dimensions of United 
i States standard, 117. 

United Slates standard, forged or 
unfinished, 116. 
Bolts, nuts and polygons, examples in, 

1 Bow pen, applying the ink to, 46. 
I large, with a removable leg, 22. 

Brass, representation of, by cross-hatch- 
1 ing, 82. 
I Bread for rubbing out, 26. 

Bristol board, use of rubber on, 26. 
! Brush-shading, 281. 

Brushes, size and use of, 280. 

Cam, a, and a lever arm in one piece 
j on a shaft, a shoe sliding on the 

I line, and held again.st the cam 

face by the rod, to find th.- po- 
sition of the face of the shoe 
against the cam, 228. 
a full stroke, method of drawing 

or marking out, 237-241. 
designed to cut off steam at five- 
eighths of the piston stroke, 
244-246. 
heart, to draw, 75, 76. 
object of using, instead of eccen- 
i trie, 234. 

(305) 



3o6 



INDEX. 



Cam wrist plate, and cut-off mechanism, 

301. 
Cams, cut-off, employed instead of ec- 
centrics on steamboats, examples 
in drawing, 232. 
finding the essential pohits of 

drawings of, 241-244. 
necessary imperfections in the op- 
erations of, 247-249. 
part played by the stroke of the 
engine in determining the con- 
formation of, 241. 
' three-fourths and seven-eighths, 
246, 247. 
Cap nut, to pencil in a, 145. 
Cast iron, representation of, 277. 

representation of by cross-hatch- 
ing, 82. 
Centre from which an arc of a circle has 

been struck, to find, 52. 
Centre of a circle, 51. 
Centre punch in which the flat sides 
run out upon a circle, the edges form- 
ing curves, 150. 
Chamfer circles of bolt heads, 120-123. 
of Franklin Institute bolt head, 
119. 
Chord of an arc, 50. 
Chuck plate with six slots, to draw, 131. 
Circle, degrees of a, 52-55. 

pencil and circle pen, u^e of, 43, 

44. 
pens, 37, 38. 
that shall pass through any three 

given points, to draw, 51. 
to divide into six divisions, 56, 57. 
Circles, lo divide with the triangle, 129. 
for bolt heads, to draw, 128. 
German instrument for drawing, 

44, 45- 
use of the instrument in fornnng, 

42-45- 
Circular arcs, Rankine's process for 

rectifying and subdividing, 210. 
Circumference, 50. 
Collar, a representation of, 96. 



Coloring and shading, points to be ob- 
served in, 278. 
Color, to maintain an even shade of, 

278. 
Colors, mixing, 278, 
Condenser, independent, 288. 
Cone, cylinder inierseciing a, 186. 
Connecting rod, 169, 295, 303. 

drawing representing the motion 
which a crank imparts to a, 249, 
250. 
end, 147. 
Copper, representation of, 277. 
Corner where the round stem meets 

the square under the head, 150. 
Coupling rod, working drawings of a, 

169. 
Crank, drawing representing the motion 
which it imparts to a connect- 
ing rod, 249. 
pin and wheel, 294. 
Cross-hatching or section lining, 77- 
82. 
made to denote material of which 

the piece is composed, 81, 82. 
may sometimes cause the lines of 
the drawing to appear crooked 
to the eye, 80, 81. 
representation by, of a section ot 
a number of pieces one within 
the other, the central bnre be- 
ing filled with short plugs, 78, 

79- 

representation by, oi three pieces 

put together, having slots or 

key-ways through them, 79, 80. 

the diagonal lines in, should not 

meet the edges of the piece, 78. 

Cross-head, 301. 

Cros>, use of, to designate a stjuare, 95, 

90. 
Cube, with a hole passing through it, 

to draw, lOl, I02. 
Cupped ring, representation '.^'i, qS. 
Curved ouilino, reprcsenlaiion of, 86, 
87. 



INDEX. 



307 



Curve for tooth face, how to find, 198. 
representation of the radius for, 
87. 
Curves and line?, 48-76. 

of gear teeth, names of, I93. 
Curves for moulding cutter, to find the, 
257-263. 
of thread, template for drawing, 

165. 
of wheels, construction, to find, 

204. 
screw threads, drawing, 159. 
templates called, 21. 
use of, in practice, 21. 
Cut-ofF cams, employed instead of ec- 
centrics on steamboats, exam- 
, pies in drawing, 232. 

manner of finding essential points 

of drawings of, 241—244. 
necessary imperfections in the op- 
erations of, 247-249. 
part played by the stroke of the 
engine in determining the con- 
formation of, 241. 
Cut-ofF mechanism, 301. 
Cutting tool for a planing machine, 

representation of, 264-266. 
Cylinder, 299. 

a solid, representation of, 94, 95, 
intersecting a cone, 186 
of an engine, 299-301. 
of an engine, drawing of, 289. 
Cylindrical body joining another at a 
right angle, a, 180. 
body whose top face, if viewed 
from one point, would appear 
as a straight line, or if from an- 
other as a circle, 188. 
piece of wood, which is to be 
squared, and each side of which 
square must be an inch, to find 
the diameter, 136. 
pieces and cubes, representation 

of. 95- 
pieces, representation of, by cross- 
hatching, "]"], 78. 



Cylindrical pieces, representation of 
three, one within the other, by 
cross-hatching, 78. 

pieces that join each other, repre- 
sentation of, 86. 

pin line-shaded, representation of, 
86. 

Decagon, a, 63. 

Degrees of a circle, 52-55. 

Diameter of a cylindrical piece of 
wood, which is to be squared, and 
each side of which square must meas- 
ure an inch, to find, 136. 

Diamond, a, 59, 60. 

Different views, arrangement of, 94- 
III. 

Dimension figures in mechanical draw- 
ing, 91. 

Dimensions, marking, 91-93. 

Distances, relative from the eye, repre- 
sentation of, by line-shading, 89. 

Dodecagon, a, 63. 

Dotted lines, use of, 48. 

Double eye, or knuckle-joint, pencil 
lines for, 146. 
or knuckle-joint, with an offset, 

147. 
Double thread, 156. 
Drawing board, 17, 18. 

fastening the drawing to, 278. 

size of, 18. 

small, advantage of, to student, 18. 
Drawing for engraver on wood, 268. 

gear wheels, 193-222. 
Drawing instruments, 22-26. 

parts of, 34. 

selecting and testing, 22. 
Drawing paper, 26-29. 

different qualities, kinds and forms, 
26, 27. 

location of on the drawing board, 
28, 29. 
Drawing the curves for screw threads, 

159- 
to scale, making a, 177. 



308 



INDEX. 



Drawings for engraving, necessity of 
conforming to the particular 
process of, 266. 
for engravings by the wax process, 
268, 269. 
Drawings for photo-engraving, 266. 
for the blacksmith, 172. 
shading and coloring, 277-288. 
Drilling machine, a boiler, 269, 270. 

Eccentric and strap, 301. 

to find how much motion it will 
give to its rod, 223. 
Edge view of a wheel, to draw, 203. 
Elevation, 94. 

Ellipse, dimensions of, how taken and 
designated, 63. 
form of a true, 66. 
most correct method of drawing, 

72. 
the, 63-75. 
Elliptical figure, whose proportion of 
width to breadth shall remain the 
same, whatever the length of the 
major axis, 69. 
Emery paper, use of on the lining pen, 

37- 

Ennagon, a, 62, (^t,. 

Engine work, examples of, 289-303. 

Engine, working drawings of a 100 
horse-power, 299. 

Engravings by the wax process, draw- 
ings for, 268, 269. 

Examples for practice, 169-177 

in bolts, nuts and polygons 112- 

151- 
of engine work, 289-303. 
of work with nine sides, 135. 

Feed -motion of a Niles horizontal tool 

work boring mill, 209. 
Five-sided figure, to draw, 132, 133. 
Flanks of teeth to trace hypocycloitlcs, 

for, 200. 
Foci of an ellipse, 64. 
Franklin Institute or United States 



Standard for heads of bolts and of 
nuts, basis of, 118. 
Full stroke cam, method of drawing 
or marking out a, 237-241. 

Gear, part of, showing the teeth in, 
the remainder illustrated by circles, 
209. 

Gear teeth, names ©f the curves and 
lines of, 193. 

Gear wheels, drawing, 193-222. 

various examples for laying out, 
214-222. 

Gearing oval, construction of, 210. 

General view, 94. 

Geometrical terms, simple explanation 
of, 48. < 

Geometry, advantage of to the draughts- 
man, 48. 

Governor of an engine, 292, 293. 

Guide bolts from one pulley to another, 
arrangement of idle pulleys to, 264. 

Heart cam, to draw, 75, 76. 
Hexagon, a, 62, 63. 

head, representation of a piece 

with, 96. 
head, to draw the end view of, 

125, 126, 127. 
headed screw, to draw, 113, 114. 
radius across corners, 138. 
Hexagonal form, representation of, 98. 
or hexagon heads of bolts, 1 1 8, 
119. 
Hole., representation of by shade or 

shadow line, 83. 
Hollows in connection with round 

pieces, representations of, S7-S9. 
Hypocycloides for the tlanks of teeth, 
to trace, 200. 

Independent condenser, 28S. 

India ink, advnntages of in drawing, 30. 

difference l>et\vcen good and infe- 
rior, 3 1 . 

good, characteristics of, 31. 



INDEX. 



309 



India ink, Higgins', 30. 

mixing, 25. 

testing, 31, 32. 

the two forms of, 30. 

to be used thick, 32. 

use of, 30, 

use of on parchment, 32. 
Ink, applying, to the bow pen, 46. 

for drawing, 30-33. 
Instruments, preparation and use of, 

34-47- 
Iron planing machine, representation 

of, 282. 
Iron, wrought and cast, representation 

of by cross-hatching, 82. 

Journal, 294. 
Journals of shafts, 277. 

Key, a, drawn in perspective, 92, 93. 
drawing of a, 91. 
marking the dimensions of on a 

drawing, 92. 
representation of with a shade line, 
84. 
Knuckle-joint, pencil eye for, 146. 
with an off-set, 147. 

Large bow or circle pen, joints of, 

23- 
Lathe centre, representation of, 86. 
Lathe feed motion, drawing of a part 

of a, 208. 
Lead pencils for drawing, 23. 
Lead, representation of by cross-hatch- 
ing, 82. 
Left-hand thread, 156. 
Lever, a, actuating a plunger in a verti- 
cal line, to find how much a 
given amount of motion of the 
long arm will actuate the 
plunger, 226. 
and shaft, drawing, 103, 104, 105. 
arm and cam, in one piece on a 
shaft, a shoe sliding on the line, 
and held against the cam face 



by the rod, to find the position 
of the face of the shoe against 
the cam, 228. 
example of the end of a, acting 

directly on a shoe, 225. 
to find how much a given amount 
of motion of a long arm will 
move the short arm of a lever, 
224. 
Levers, two, upon their axles or shafts, 
the arms connected by a link, and 
one arm connected to a rod, 227. 
Light in shading, 280. 

management of, in mechanical 
drawing, 82, 83. 
Line-shaded engravings, drawing for, 

264-276. 
Line-shading, 77-90. 

and drawing for line-shaded en- 
gravings, 264-276. 
in perspective drawing of a pipe- 
threading stock and die, 85. 
mechanical drawing made to look 
better and show more distinctly 
by, 82. 
simplest form of, 82 
Lines and curves, 48-76. 
Lines in pencilling, where to begin, 

24, 25. 
Lining pen, 22. 
Lining pen, form of, 34-37. 
Lining pen, use of with a T square, 45, 

47- 
Link introduced in the place of a roller, 
to find the amount of motion of 
the rod, 226. 
quick return, plotting out the mo- 
tion of a shaper, 250-253. 
Links, pencilling for, 145, 146. 
Locomotive frame, 174. 
spring, 169. 

Machine screw, to draw, 112, 1 13. 
Main journal, 294. 
Marking dimensions, 91-93. 
Measuring rules, draughtsman's, 33. 



3IO 



INDEX. 



Mechanical motions, plotting, 223-263. 
Motion an eccentric will give to its 
rod, to find, 223. 
a shaper link, quick return, plot- 
ting out, 250-253. 
imparted in a straight line to a 
rod, attached to an eccentric 
' strap, to find the amount of, 

229-231. 
which a crank imparts to a con- 
necting rod, 249, 250. 
Motions, plotting mechanical, 223-263. 
Moulding cutter, finding the curves for, 
257-263. 

Niles' horizontal tool work boring mill, 

feed motion of a, 209. 
Nonagon, a, 62. 

Nut, a representation of the shade line 
% on, 84. 

cap, to pencil in a, 145. 
to show the thread deplh in the 
top or end view of a, 166, 
Nuts' and bolts, dimensions of United 

States Standard, 117. 
Nuts and polygons, examples in, 112- 

Octagon, a, 62, 63. 

Oil cup, representation of, 282, 284. 

Outline views, 97, 98. 

Oval gearing, construction of, 210. 

Paper cutter, the form of the end of, 

25. 

rules or scales, 32. 
Parabola, to draw by lines, 74, 75. 

to draw mechanically, 73, 74. 
Parallel lines, 49. 
Parallelogram, 59, 60. 
Parchment, use of India ink on, 32. 
Pen, German, regulated to draw lines 
of various breadths, 84, 85. 

lining, form of, 34-37. 
Pen point, forming the, 39, 40. 

form of recently introduced, 39. 



Pen points, oilstoning, 36. 
Pen, with sapphire points, 85. 
Pens, circle, y] , 38, 

used in drawing, 22. 
Pencil holders for sticks of lead, 24. 

lines in drawing, 23. 

sharpening for fine work, 24. 
Pencilling for a link, having the hubs 
on one side only, 145. 

in a cap nut, 145, 
Penknife and rubber scratching out, 

25- 
Pentagon, a, 62, 63. 
Perimeter, the, 50. 
Periphery, 50. 
Perpendicular line, 49. 
Perspective sketches to denote the shape 

of the piece, 93. 
Photo-engraving, drawings for, 266, 

267. 
Piece of work should, in mechanical 

drawing, be presented in as few views 

as possible, 94. 
Pillow block box, 294. 
Pin, in a socket, in section, representa- 
tion of, 87, 88. 
Pinion teeth, to draw to the pitch of 

the inner and small end of, 206. 
Pins and discs, discrimination of, in 

mechanical drawing, 96. 
Pipe threading stock and die, drawing 

of, 85. 
Pitch circle of the inner and small end 
of, to draw, 206. 
to obtain a division of the lines 
that divide, 167. 
Plan, 94. 
Planing machine, a cutting tool for, 

264-266. 
Plotting mechanical motions, 223-263. 
out the motion of a shaper hnk 
quick return, 250-253. 
Point, a, 49. 

Points of drawing instruments, 34. 
Polished surfaces, to show by shading, 

282. 



INDEX. 



311 



Polygon of twelve equal sides, to draw, 

129, 130. 
Polygons, bolts and nuts, examples of, 
1 12-15 1, 
construction of, 61. 
designation of the angles of, 62. 
names of regular, 62, 63. 
scales giving the lengths of the 
sides of, 135. 
Preparation and use of the instruments, 

34-47- 
Produced line, 50. 

Projecting one view from another, 106. 
Piojections, 1 78-192. 
Protractors, 53. 

Pulley, Medart, shading a, 280. 
Pulleys, arrangement of idle, to guide 

bolts from one pulley to another, 

264. 

Quadrangle, quadrilateral or tetragon, 

59. 

Quadrant of a circle, 50. 

Quick return moiion, ^Vhitworth, plot- 
ling out, 253-256. 

Radius across corners of a hexagon, 

138. 
Rankine's process for rectifying and 

subdividing circular arcs, 210. 
Reducing scales, 175. 
Rectangle, a, 59, 60. 
Rectangular piece, a, to draw in two 
views, 98, 99. 
requires two or three views, 96, 

97- 
representation of, 96. 

Red ink, marking dimensions of me- 
chanical drawings in, 91. 

Rhomboid, a, 60. 

Rhomb, rhombus or diamond, 54, 60. 

Right line, a, 49. 

Ring with a hexagon cross section, 98. 

Rivet, side and end views of, 49. 

Roller, example of a short arm having 
a, acting upon a larger roller, 225. 



Rod, attached to an eccentric strap, to 
find the amount of motion im- 
parted in a straight line to a, 
229-231. 

end with a round stern, 14S. 
Round stem, a representation of, 96. 

lop and boitom thread, 156. 
Rubber, 25. 

form of, 26. 

proper uses of, 23. 

sponge, 26. 

the use of, 25. 

to be used on Bristol board, 26. 

velvet, 26. 
Rule, steel, 32, 



Sapphire points, pen with, 85. 
Scale for diameter ot a regular polygon, 
140. 
of tooth proportions, 195. 
triangular, t^t^. 
Scales, for measurement and drawing, 
32. 
reducing, 175. 
Scratching out, 25. 
Screw machine, to draw, 112, 113. 

thread. United States standard, to 

draw, 159-160. 
threads and spirals, 152-168. 
threads, drawing the curves for, 

159- 
threads for small bolts, with the 
angles of the threads drawn in, 

152-155- 
threads of a large diameter, 156.. 
Section lining or cross-hatching, 77- 

82. 
Sectional view of a section of a wheel, 
for showing dimensions through arnih 
and hub, 202. 
Sector of a circle, 51. 
Segment of a circle, 50. 
Semicircle, 51. 

Shade curve, representation of, 87. 
line produced for circles, 84. 



312 



INDEX. 



Shade line, produced in straight lines, 
84. 
or shadow line, 82. 
Shading a Medart pulley, 280. 

and coloring, points to be observed 

in, 278. 
brush, 281. 

by means of lines to distinguish 
round from flat surfaces, and 
denote relative distances of sur- 
faces, 85. 
example in, of a Blake's patent 
direct acting steam pump, 284, 
285. 
example of, in an independent 

condenser, 288. 
light in, 280. 
simple, 277. 

to show by, that the surfaces are 
highly polished, 282. 
Shadow line, 82. 

lines and line shading, 77-90. 
Shaft for cam plate, 301. 
Shaper link, quick return, plotting out 

the motion of a, 250-253. 
Shoe against a cam, to find the position 

of the face of, 228. 
Side elevation, drawing a, 106. 
Sides or flats of work, to find the lengths 

of, 135, 136. 
Slots not radiating from a centre, to 
draw, 131, 132. 
radiating from a centre, 131. 
Spiral spring, to draw, 166. 
Spiral wound I'ound a cylinder, whose 

end is cut off at an angle, 178. 
Spirals and screw threads, 1 52-168, 
?ponge, rubber, 26. 
'pring bow pencil, for circles, 22. 

pen, for circles, 22, 23. 
S])ring, spiral, to draw, 166. 
Spur wheel teeth, how to draw, 194. 
Square, a, 59, 60. 

body, which measures one inch 
on each side, to find what it 
measures across the corners, 136. 



Square part, a representation of, 96. 
parts, use of a cross to designate, 

95, 96. 
thread, to draw a, 162-164. 
Steam boiler, horizontal, for stationary 
engine, 296. 
chest and valves, 301. 
chest side, and horizontal cro^s 

section of cylinder, 301. 
pump, Blake's patent direct act- 
ing, 284, 285. 
Steel, representation of, 277. 

representation of by cross-hatch- 
ing, 82. 
square, improved, with pivoted 
blade, 19. 
Steps, to draw a piece containing, 99- 

loi. 
Slock and die, pipe-threading, drawing 

of, 85. 
Straight line in geometry termed a 
right line, 49. 
or lining pen, use of with a T 
st]uare, 45, 47. 
Stud, to draw a, 142. 
Stuffing-box and gland, 169. 
Surface of the paper, condensing after 

rubbing out, 25. 
Surfaces, highly polished, to show by 
shading, 282. 

Tacks for drawing paper, 27, 28. 
Tangent, 51. 

Taper or conical hole, to denote in 
drawing, 102. 
sides in a drawing, 102, 103. 
Tees, 180. 

Teeth of wheels, rules for drawing, 
203. 
pinion, to draw tlie pitch of the 

inner and small end of, 206, 
spur wheel, how to draw, 194. 
to trace hypocycloides for the 
flanks of, 200. 
Template for drawing the curves of 
thread, 165. 



J 



INDEX. 



313 



Templates called curves, 21. 
T square, 18, 19. 
T squares, different kinds of, 19. 
Tetragon, a, 59, 62, 63. 
Thread, a double, 156. 

a round top and bottom, 156. 

depth in the top or end view of a 
nut, to show, 166. 

left hand, 156. 

square, to draw a, 162-164. 

Whitworth, 156. 
Threads of a large diameter, 1 56. 
Thumb tacks for drawing paper, 27. 
Tint, to graduate the depth of, for a 

cylindrical surface, 279. 
Tooth face, how to find the curve for, 
198. 

proportions, Willis' scale of, 195. 
Tracing cloth, 29. 

paper, 29. 
Trammel, use of in drawing an ellipse, 

72. 
Trapezium, 60. 
Trapezoid, a, 60. 
Triangle, equilateral, 58, 59. 

isosceles, 58, 59. 

obtuse, 58, 

right angle, 58, 

scalene, 59. 

use of in dividing circles, 129. 

use of in drawing polygons, 129, 
130. 

use of to draw slots radiating from 
a centre, 131. 
Triangles, 19-21,58-60. 

requirements in use of, 20, 21. 

to draw, 133. 

using with the square, 20. 
Triangular scale, '})'h- 
Trigon, a, 62, 63. 

True ellipse, a near approach to the 
form of, 69-72. 



United States standard bolts and nuts, 
114-118. 
standard thread, to draw, 159, 160. 

Valve of an engine, 290-292. 
Valves, 301. 
Vertex, the, 59. 

Views, different arrangement of, 94- 
III. 
of a piece of work, designations 

of, 103, 104. 
of a piece, two systems of placing, 
106-111. 

Washer, a, representation of the shad- 
ow side of, 83. 
Wax process, drawings for engravings 
by, 268, 269. 
engraving from a print from a 
wood engraving, 269. 
Wedge-shaped piece, representation of 

a, 97. 
Wheel, edge view of a, to draw, 203. 
sectional view of a section of a, 
202. 
Wheels, construction, to find the curves 
of, 204. 
to draw the arcs for the teeth of, 
205. 
Whitworth thread, 156. 

quick return motion, plotting out, 
253-256. 
Willis' scale of tooth proportions, 195. 

application of, 197. 
Wood engraving, drawing for, 268. 
Wood, representntion of by cross- 
hatching, 82. 
representation of, regular and ir- 
regular shade lines in, 90. 
Wrought iron, representation of, 277. 
representation of by cross-hatch- 
ing, 82. 



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ARLOT.— A Complete Guide for Coach Painters. 

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""^"^RMENGAUD, AMOROUX, and JOHNSON.— The 
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ARROWSMITH.— Paper-Hanger's Companion : 

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ASHTON.— The Theory and Practice of the Art of De- 
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BAIRD.— Letters on the Crisis, the Currency and . the 
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BAIRD.— Protection of Home Labor and Home Pro- 
ductions necessary to the Prosperity of the Ameri- 
can Farmer. 
By Henry Carey Baird. 8vo., paper 10 

BAIRD.— Some of the Fallacies of British Free-Trade 
Revenue Reform. 

Two Letters to Arthur Latham Perry, Professor of History and Politi- 
cal Economy in Williams College. By Henry Carey Baird. 
Pamphlet 05 

BAIRD.— The Rights of American Producers, and the 
Wrongs of British Free- Trade Revenue Reform. 
By Henry Carey Baird. Pamphlet 05 

BAIRD.— Standard Wages Computing Tables : 

An Improvement in all former Methods of Comjiutatior, so arranged 
that wages for days, hours, or fractions of hours, at a specified rstte per 
day or hour, may be ascertained at a glance. By T. SrANGLKU B a i k n. 
Oblong folio $5.00 

BAIRD.— The American Cotton Spinner, and Mana- 
ger's and Carder's Guide : 
A Practical Treatise on Cotton S])inning; giving the Dimensions ajid 
Speed of MacliiiuM-y, Draug'it and Twist Calcnhitions, etc. ; with 
notiiM'S of recent Improvcnients : togellier with IJnh's and Ivxaniplea 
for jnaking cliani^'cs in (he sizes and ninnhcrs oC Itoving and Yarn. 
Comi)iled from tiu' ])ai)er.s of the late Bobkut 11. Baird. V2mo. ;^l,50 



HENRY CAREY BAIRD'S CATALOGUE. S 

BAKER.— Long-Span Railway Bridges : 

Com]>i-isinix lnve>tiirati(»ns <»t" the (\»m|>araiive Tlfeoretieal and Prac- 
tical Advauraiffs of tlir various Adopted or Proposed Type {Systems 
of (.'oiistruetiou ; with numerous Formulae and Tables. By B. Baker. 
12mo $2.00 

BAUERMAN.— A Treatise on the Metallurgy of Iron : 

Containing Outlines of the History of Iron Manufacture, Metliods of 
Assay, and Analysis of Iron Ores, Processes of Manufacture of Iron 
and Steel, etc., etc. By H. Bai^kkman, F. G. S., Associate of the 
Royal School of Mines. First American Edition, Revised and En- 
larged. With an Appendix on the ^Martin Process for Making Steel, 
from the Report of AiiKAM S. Hewitt, U. S. Commissioner to the 
Universal Exposition at Paris, 18(37. Illustrated. 12mo. . $2.00 

BEANS.— A Treatise on Railway Curves and the Loca- 
tion of Railways. 
By E. W. Beans, C. E. Illustrated. 12mo. Tucks. . . $1.50 

BELL.— Carpentry Made Easy : 

Or, The Science and Art of Framing on a New and Improved Systfm. 
With Specific Instructions for Building Balloon Frames, Barn Frames, 
!Mill Frames, Warehouses, Church S])ires, etc. Comi)rising also a 
System of Bridge Building, Avith Bills, Estimates of Cost, and valuable 
Tables. Illustrated by 38 plates, comprising nearly 200 figures. By 
William E. Bell, A^rchitect and Practical Builder. 8vo." . $5.00 

BELL.— Chemical Phenomena of Iron Smelting : 

An Experimental and Practical Examination of the Circumstances 
which determine the Capacity of the Bhist Furnace, the Temperature 
of the Air, and the pro])er Condition of the Materials to be operated 
upon. By I. Lowthian Bell. Illustrated. 8vo. 

BEMROSE.— Manual of Wood Carving : 

With Practical Illustrations for Learners of the Art, and Original and 
^elpfted Desiirns. Bv WiLLiAM Bemeose, Jr. With an Introduction 
by Llewellyn Jewitt, F. S. A., etc. Witii 128 Illustrations. 4to., 
cioth $3.00 

BICKNELL.— Village Builder, and Supplement : 

Elevations and Plans for Cotta-es, Villas, Suburban Eesidences, 
Farm Houses, Stal'iles and Carriage Houses Store Fronts, School 
Houses, Churches, Court Houses, and a model Jail ; also, Exterior and 
Interior details for Public and Private Buildings, witli ajijiroved 
Forms of Contracts and Specifications, including Prices of Building 
Materials and Labor at Boston, Mass., and St. Louis, Mo. Containing 
75 plates drawn to scale; showing the style and cost of building in 
different sections of the country, being an original wov'c comprising 
the designs of twentv leadinc: architects, representing the New Eng- 
land, Middle, Western, and Southwestern States. 4to. . •$10.'00 



4 HENRY CAREY BAIRD'S CATALOGUE. 

BIiENKARN.— Practical Specifications of Works exe- 
cuted in Architecture, Civil and Mechanical Engi- 
neering, and in Road Making and Sewering : 

To which are added a series of practically useful Agreements and Re- 
ports. By John Blenkarn. Illustrated by 15 large folding plates, 
8vo. $9.00 

BLINN.— A Practical Workshop Companion for Tin, 
Sheet-Iron, and Copperplate Workers : 

Containing Rules for describing various kinds of Patterns used by 
Tin, Sheet-Iron, and Copper-plate Workers; Practical Geometry'; 
Mensuration of Surfaces and Solids ; Tables < f the Weights of Metals, 
Lead Pipe, etc. ; Tables of Areas and Circumferences of Circles ; 
Japan, Varnishes, Lackers, Cements, Compositions, etc., etc. By 
Leroy J. BuNN, Master Mechanic. With over 100 Illustrations. 
12mo $2.50 

BOOTH.— Marble Worker's Manual : 

Containing Practical Information respecting Marbles in general, their 
Cutting, Working, and Polishing ; Veneering of Marble ; Mosaics : 
Composition and Use of Artificial Marble, Stuccos, Cements, Receipts, 
Secrets, etc., etc. Translated from the French by M. L. Booth. 
With an Appendix concerning American Marbles. 12rao., cloth. $1.50 

BOOTH AND MOB,FIT.— The Encyclopedia of Che^ 
mistry, Practical and Theoretical : 

Embracing its application to the Arts, Metallurgy, Mineralogy, Gev 
ology, Medicine, and Pharmacy. By James C. Booth", MelteV and 
Refiner in the United States Mint, Professor of Applied Chemistry in 
the Franklin Institute, etc., assisted by Campbell Morfit, author 
of " Chemical Manipulations," etc. Seventh edition. Royal 8vo., 
978 pages, with numerous wood-cuts and other iHustrations. " ". $5.00 

BOX.— A Practical Treatise on Heat: 

As applied to tlie Useful Arts ; for the Use of Engineers, Architects, 
etc. By Thomas Box, author of " Practical Hydraulics." Illustrated 
by 14 plates containing 114 figures. 12mo. .' . . . $5.00 



BOX.— Practical Hydraulics : 

A Series of Rules and Tables for the use of Engineers, etc. Bv 
Thomas Box, 12mo, . . . . . , " , . $2.00 

BROWN.— Five Hundred and Seven Mechanical 
Movements : 
Embracing all those which are most imnortant in Dynamics, TTydrau- 
lics, llydrost'itics, Piu'umafics, Steaui I'.tigines, Mill ami other (.car- 
ing. Presses, Horology, and Misccliaueous Maciiiuery ; and including 
many movemcMits never before ]>ublished, ami several of which have 
only recently conu^ into use. !{y 1Ii:nky T. Hkown, Editor of the 
" American Artisan." In one voiunie, IJino, . . $1.(K> 



HENRY CAREY BXIRD'S CATALOGUE. 6 

BUCKMASTER.— The Elements of Mechanical Phy- 
sics : 
Bv J. C. BucKMASTER, late Student in the Goveriniient School of 
Mines ; Certified Teaeher of Science by the Departn^ont of Science 
and Art; Examiner in Chennstry and Physics in the Koyal Colleuce 
of Precei)tors; and late Lecturer in Chemistry and Physics of tlie 
Ivoyal Polytechnic Institute. Illustrated with numerous engravings. 
In one volume, 12mo. . . i^iLJU 

BULLOCK.— The American Cottage Builder : 

A Series of Designs, Plans, and Sjiecifications, from 8200 to $20,000, 
for Homes for the People; together with Warming, Ventilation, 
Drainage, Painting, and Landscape Gardening. By JoiiN BuLLOCK, 
Architect, Civil Engineer, Mechanician, and Editor of " The Pvudi- 
ments of Architecture and Building," etc., etc. Illustrated by 75 en- 
gravings. In one volume, 8vo $3.50 

BULLOCK. — The Rudiments of Architecture and 
Building : 
For the use of Architects, Builders, Draughtsmen, ^Machinists, Engi- 
neers, and Mechanics. Edited by Joiix lU'LLOCK, author of '' The 
American Cottage Builder." Illustrated by 250 engravings. In one 
volume, Svo ' . . . . $3.50 

BURGH. — Practical Illustrations of Land and Marine 
Engines : 
Showing in detail the ^lodern Improvements of High and Low Pres- 
sure, Surface Condensation, and Super-heating, together wit i Land 
and Marine Boilers. By X. P. BrnoH, Engineer. Illu^tn ted hy 
20 plates, double elephant folio, with text. . . . S2l.0'0 

BURGH.— Practical Rules for the Proportions Ox Mo- 
dern Engines and Boilers for Land and Marine 
Purposes. 
By N. P. Burgh, Engineer. 12mo $1.50 

BURGH.— The Slide-Valve Practically Considered. 
By X. P. BURGII, Engineer. Completely illustrated. 12mo. $2.00 

BYLES.— Sophisms of Free Trade and Popular Politi- 
cal Economy Examined. 
By a Barrister (Sir Joiix Barnard Byles, Judge of Common 
Pleas). First American from the Ninth English IZdition, as published 
by the [Manchester Reciprocity Association. In one volume, 12mo. 

$L25 

IBYRl^.— The Complete Practical Brewer : 
Or Plain, Accurate, and Thorough Instructions in the Art of Brewing 
Beer, Ale, Porter, including the Process of making Bavarian Beer, 
all the Small lieers, such as Root-beer, Ginger-pop, Sarsai)anlla- 

• beer, ^fead. Spruce Beer, etc., etc. Adapted to the use of Public 
Brewers and I'rivate Families. By M. La Fayette Byrn, M D. 
With illustrations. 12mo §1.25 



6 HENRY CAREY BAIRD'S CATALOGUE. 

B YRN.— The Complete Practical Distiller : 

Comprising the most perfect and exact Theoretical and Practical De- 
scription of the Art of Distillation and Rectification ; including all of 
the most recent improvements in distilling apparatus ; instructions 
for preparing spirits from the numerous vegetables, fi'uits, etc. ; direc- 
tions for the distillation and preparation of all kinds of brandies and 
other spirits, spirituous and other compounds, etc., etc. By M. La 
Fayette Byrn, M. D. Eighth Edition. To which are added, Prac- 
tical Directions for Distilling, from the French of Th. Fling, Brewer 
and Distiller. 12mo. . " $1.50 

BYRNE. — Handbook for the Artisan, Mechanic, and 
Engineer : 

Comprising the Grinding and Sharpening of Cutting Tools, Abrasive 
Processes, Lapidary Work, Gem and Glass Engraving, \'arnishing 
and Lackering, Apparatus, Materials and Processes for Grinding and 
Polishing, etc. By Oliver Byrne. Illustrated by 185 wood en- 
gravings. In one volume, 8vo. . . . ' . ' . . $5.00 

BYRNE.— Pocket Book for Railroad and Civil* Engi- 
neers : 

Containing New, Exact, ai)d Concise Methods for laying out Rail- 
road Curves, Switches, Frog Angles, and Crossings ; the Staking 
out of work; Levelling; the Calculation of Cuttings; Embankments; 
Earth-work, etc. By "Oliver Byrne. 18mo., full bound, pocket- 
book form $1.75 

BYRNE.— The Practical Model Calculator : 

For the Engineer, Mechanic, Manufacturer of Engine Work, Naval 
Architect, Miner, and Millwright. By Oliver Byrne. 1 volume, 
8vo., nearly 600 pages_ $4.50 

BYRNE.— The Practical Metal-Worker's Assistant: 

Comprising ]\Ietallurgic Chemistry ; the Arts of Working all ]\letals 
and Alloys; Forging of Iron and Steel; Hardening and Temi)ering; 
Melting and Mixing; Casting and Founding; Works in Sheet Metal; 
The Processes Dependent on the Ductility of the Metals; Soldering; 
and the most Improved Processes and 'Tools emi)loyed by Metal- 
workers. With the A})plication of the Art of Electro-Metallurgy to 
Manufacturing Processes; colh^cted from Original Sources, and from 
the Works of lloltzapffel, Hergeron, Leuj)old, Plumier, iS'n])ier, 
Scoffern, C'lay, Fairbairn, and otliers. By Oliver Byrne. A new, 
revised, and "improved edition, to which is added An Appendix, con- 
taining TlIK J^LVNIIKACTUKE OK RUSSIAN SIIEET-IRON. By JoiIN 

Pkrcy, M. D., F.R.S. The Manukactuke ok Malleaul'e Ikon 
(,'ASTiN(Js, and Lmi'Iiovemknts in Hesskmek Stkkl. ]W a. a. 
Fesquet, Chemist and Engineer. With over ()00 Engravings, illus- 
trating every Jiranch of the Subject. 8vo $7.00 

Cabinet Maker's Album of Furniture : 

Coniprisins, a Collccliou of Designs (or Fninilure. Illustrated by 48 
Large and Beautifully Engraved IMatcs. In one vid., oblouj; ij^^.oO 



i 



HENRY CAREY BAIRD'S CATALOGUE. 7 

CALLINGHAM.— Sign Writing and Glass Emboss- 
ing: 
A C(>nii)lete Practical Illustrated Manual of the xirt. By James 
Callingiiam. In one volume, 12mo $1.50 

CAMPIN. — A Practical Treatise on Mechanical Engi- 
neering : 

Comprising Metallurgy, ]\Ioul(ling, Casting, Forging, Tools, Work- 
shop Machinery, Mechanical Mani])ulation, Manufacture of Steam- 
engines, etc., etc. With an Ajjpendix on the Analysis of Iron and 
Iron Ores. By Francis Campix, C. E. To which are added, Obser- 
vations on the Construction of Steam Boilers, and Remarks upon 
Furnaces used for Smoke Prevention ; with a Chapter on Ex])l()si()ns. 
By R. Armstrong, C. E., and John Bourne. Rules for Calculating 
the Change Wheels for Screws on a Turning Lathe, and for a Wheel- 
cutting Machine. By J. La Nicca. Management of Steel, Includ- 
ing Forging, Hardening, Tempering, Annealing, Shrinking, and Ex- 
pansion. And the Case-hardening of Iron. By G. Ede. tivo. Illus- 
trated with 29 plates and 100 wood engravings . . . $6.00 

CAMPIN.— The Practice of Hand-Turning in Wood, 
Ivory, Shell, etc. : 

With Instructions for Turning such Avorks in Metal as may be re- 
quired in the Practice of Turning AV^ood, Ivory, etc. Also, an Appen- 
dix on Ornamental Turning. By Francis Campin; with Numerous 
Illustrations. 12mo., cloth $2.00 

CAREY.— The Works of Henry C. Carey : 

FINANCIAL CRISES, their Causes and Effects. 8vo. paper . 25 
HARMONY OF INTERESTS: Agricultural, Manufacturing, and 

Commercial. 8vo., cloth $1.50 

MANUAL OF SOCIAL SCIENCE. Condensed from Carey's " Prin- 
ciples of Social Science." By Kate McKean. 1 vol. 12rao. $2.25 
MISCELLANEOUS W^ORKS : comprising " Harmony of Interests," 
" Money," " Letters to the President," " Financial Crises," " The 
Way to Outdo England Without Fighting Her," "Resources of 
the 'Union," "The Public Debt," ''Contraction or Expansion?" 
" Review of the Decade 1857-'67," " Reconstruction," etc., etc. 

Two vols., Svo., cloth 

PAST, PRESENT, AND FUTURE. Svo S2.50 

PRINCIPLES OF SOCIAL SCIENCE. 3 vols., Svo., cloth $10.00 
THE SLAVE-TRADE, DOMESTIC AND FOREIGN ; Why it Ex- 
ists, and How it may be Extinguished (1853). Svo., cloth . S2.00 
LETTERS ON INTERNATIONAL COPYRIGHT (1867) . 50 
THE UNITY OF LAW: As Exhibited in the Relations of Physical, 
Social, Mental, and Moral Science (1872). In one volume, Svo., 
pp. xxiii., 433. Cloth $3.50 

CHAPMAN.— A Treatise on Ropemaking : 

As Practised in private and public Rope yards, with a Description 
of the Manufacture, Rules, Tables of Weights, etc., adapted to the 
Trades, Shipping, Mining, Railways, Builders, etc. By Robert 
Chapman. 24mo * $1.50 



8 HENRY CAREY BAIRD'S CATALOGUE. 

COLBURN.— The Locomotive Engine : 

Including a Descrij^tion of its Structure, Rules for Estimating its Capa- 
bilities, and Practical Observations on its Construction and Manage- 
ment. By Zeeah COLBURN. Illustrated. A new edition. 12mo. ^1.25 

CRAIK. — The Practical American Millwright and 
Miller. 

By David Craik, Millwright. Illustrated by numerous wood en- 
gravings, and two folding plates. 8vo ^5.00 

DE GRAFF.— The Geometrical Stair Builders' Guide : 

Being a Plain Practical System of Hand-Railing, embracing all its 
necessary Details, and Geometrically Illustrated by 22 Sieel Engrav- 
ings ; together with the use of the most approved principles of Prac- 
tical Geometry. By Simon De Geaff, Architect. 4to. . $5.00 

IdE KONI]SfCK.—DIETZ.— a Practical Manual of Che- 
mical Analysis and Assaying : 

As applied to the Manufacture of Iron from its Ores, and to Cast Iron, 
Wrought Iron, and Steel, as found in Commerce. By L. L. De Kon- 
INCK, Dr. Sc, and E. Dietz, Engineer. Edited with Notes, by Robert 
Mallet, F.R.S., F.S.G., M.I.C.E., etc. American Edition, Edited 
with Notes and an Appendix on Iron Ores, by A. A. Fesquet, Chemist 
and Engineer. One volume, 12mo. $2.50 

DUNCAN.— Practical Surveyor's Guide: 

Containing the necessary ini^rmation to make any person, of common 

capacity, a finished land surveyor without the aid of a teacher. By ) 

Andrew Duncan. Illustrated. 12mo., cloth. . . . $1.25 i 

DUPLAIS.— A Treatise on the Manufacture and Dis- 
tillation of Alcoholic Liquors : 

Comprising Accurate and Complete Details in Regard to Alcohol from 
Wine, Molasses, Beets, Grain, Rice, Potatoes, Sorghum, Asphodel, 
Fruits, etc. ; with the Distillation and Rectification of Brandy, AVhis- 
key. Rum, Gin, Swiss. Absinthe, etc., the Preymration of Aromatic Wa- 
ters, Volatile Oils or Essences, Sugars, Syru]>s, Aronis^tic Tinctures, 
Liqueurs, Cordial Wines, Etfervescing \\'iiK's, etc.. tlic Aging of Brandy 
and the Improvement of Spirits, with Copious Directions and Tables 
for Testing and Reducing Spirituous Ijiquors, etc., etc. Translated 
and Edited from the French of ^MiM. Duplais, Aino, et Jeune. By 
M. M(;Kennie, M.D. To which are added tlie Unit(>d States Internal 
Revenue Regulations for the Assessment iuid Collection of Taxes on 
Distill(>d S))irits. Illustrated by fourteen folding plates and several 
wood (!iigravings. 743 pp., 8vo $10.00 

DUSSATJCE. — A General Treatise on the Manufacture 
of Every Description of Soap : 

Comprising (he CluMuistry of (he .\rt, wi(ii BiMiiarks on .\lk;ilies, Sa- 

i)oniliahle Fatty Bodices, the ap))aratiis necessary in a Soap Factory, 
'ractical liistrnctions in tlie ninmifnclure of the various kinds of Soa]>. 
the :iss;iy of So:ij)s, (•((•., etc. ICdittvl from Notes (.f ]viinii(\ lM>n(cnelle, 
l\f:il!i|);ivre, DuCoitr, and otliers, with hir','e and iniportan( additions hy 
J*rof. 11. Dushalce, Chemist. Illustrated. In one vol., ^vo. . $25.00 



HENRY CAREY BAIRD'S CATALOGUE. 9 

DUSSAUCE.— A General Treatise on the Manufacture 
of Vinegar : 

Theoretical and Practical. Comprising the various Methods, by the 
Slow and the Quick Processes, with Alcohol, Wine, Grain, Malt, Cider, 
Molasses, and Beets ; as well as the Fabrication of Wood Vinegar, etc., 
etc. By Prof. H. Dussauce. In one volume, 8vo. . . $5.00 

PUSSAUCE.— A New and Complete Treatise on the 
Arts of Tanning, Currying, and Leather Dressing : 

Comprising all the Discoveries and Improvements made in France, 
Great Britain, and the United States, Edited from Notes and Docu- 
ments of Messrs. Sallerou, Grouvelle, Duval, Dessables, Labarraque, 
Payen, Rene, De Fontenelle, Malapeyre, etc., etc. By Prof. H. Dus- 
sauce, Chemist. Illustrated by 212 wood engravings. 8vo. $25.00 

PUSSAUCE.— A Practical Guide for the Perfumer : 

Being a New Treatise on Perfumery, the most favorable to the Beauty 
without being injurious to the Health, comprising a Description of the 
substances used in Perfumery, the Formula; of more than 1000 Prepa- 
rations, such as Cosmetics, Perfumed Oils, Tooth Powders, Waters, 
Extracts, Tinctures, Infusions, Spirits, Vinaigres, Essential Oils, Pas- 
tels, Creams, Soaps, and many new Hygienic Products not hitherto 
described. Edited from Notes and Documents of Messrs. Debay, Lb- 
nel,etc. With additions by Prof. H. Dussauce, Chemist. 12mo. 

DUSSAUCE.— Practical Treatise on the Fabrication 
of Matches, Gun Cotton, and Fulminating Powders. 

By Prof. H. Dussauce. 12mo $3.00 

Dyer and Color-maker's Companion: 

Containing upwards of 200 Receipts for making Colors, on the most 
approved principles, for all the various styles and fabrics now in exist- 
ence ; with the Scouring Process, and jjlain Directions for Preparing, 
Washing-off, and Finishing the Goods. In one vol., 12mo. . $1.25 

EASTON.— A Practical Treatise on Street or Horse- 
power Railways. 

Bv Alexander Easton, C.E. Illustrated by 23 plates. 8vo., 
cloth . 13.00 

ELDER.— Questions of the Day : 

Economic and Social. By Dr. William Elder. 8vo. . $3.00 
FAIRBAIRN.— The Principles of Mechanism and Ma- 
chinery of Transmission : 
Comprising the Principles of Mechanism, Wheels, and Pulleys, 
Strength and Proportions of Shafts, Coupling of Shafts, and Engaging^ - 
and Disengaging Gear. By Sir William Fairbaien, C.E., LL.D., 
F.R.S., F.G.'S. Beautifully illustrated by over loO wood-cuts. In 

one volume, 12mo $2.50 

FORSYTH.— Book of Designs for Headstones, Mural, 
and other Monuments : 
Containing 78 Designs. By James Forsyth. With an Introduction 
by Charles Boutell, M* A. 4to., cloth. .... $5.00 • 



10 



HENEY CAREY BAIRD'S CATALOGUE. 



GIBSON.— The American Dyer: 

A Practical Treatise on the Coloring of Wool, Cotton, Yarn and 
Cloth, in three parts. Part First gives a descriptive account of the 
Dye Stuffs; if of vegetable origin, where produced, how cultivated, 
and how prepared for use; if chemical, their composition, specific 
gravities, and general adaptability, how adulterated, and how to de- 
tect the adulterations, etc. Part Second is devoted to the Coloring of 
Wool, giving recipes for one hundred and twenty-nine different colors 
or shades, and is supplied with sixty colored samples of Wool. Part 
Third is devoted to the Coloring of Raw Cotton or Cotton Waste, for 
mixing with Wool Colors in the Manufacture of all kinds of Fabrics, 
gives recipes for thirty-eight different colors or shades, and is supplied 
with twenty-four colored samples of Cotton Waste. Also, recipes for 
Coloring Beavers, Doeskins, and Flannels, with remarks upon Ani- 
lines, giving recipes for fifteen different colors or shades, and nine 
samples of Aniline Colors that will stand both the Fulling and Scour- 
ing process. Also, recipes for Aniline Colors on Cotton Thread, and 
recipes for Common Colors on Cotton Yarns. Embracing in all over 
two hundred recipes for Colors and Shades, and ninety -four samples 
of Colored Wool and Cotton Waste, etc. By Richard H. Gibson, 
Practical Dyer and Chemist. In one volume, 8vo. . . $6.00 

GILBART.— History and Principles of Banking : 

A Practical Treatise. By James W. Gilbaet, late Manager of the 
London and Westminster Bank. With additions. In one volume, 
8vo., 600 pages, sheep $5.00 

Gothic Album for Cabinet Makers : 

Comprising a Collection of Designs for Gothic Furniture. Illustrated 
by 23 large and beautifully engraved plates. Oblong . . $2.00 

GRANT. — Beet-root Sugar and Cultivation of the 
Beet. 

By E. B. Grant. 12mo . $1.25 

GREGORY.— Mathematics for Practical Men : 

Adapted to the Pursuits of Surveyors, Architects, Mechanics, and 
Civil Engineers. By Olinthus Gregory. 8vo., plates, cloth $3.0(i 

GRISWOLD.— Railroad Engineer's Pocket Compan- 
ion for the Field : 

Comprising Rules for Calculating Deflection Distances and Angles, 
Tangential Distances and Angles, and all Necessary Tables for Engi- 
neers ; also the art of Levelling from Preliminary Survey to the Con- 
struction of Railroads, intended Expressly for the Young Engineer, 
together with Numerous Valuable Rules and Exanii)ies. By W. 
Griswold. 12mo., tucks $1.75 

GRUNER.— Studies of Blast Furnace Phenomena. 

By M. L. (ilUiNKR, President of the (Jeneral Council of T>nnos of 
France, and lately Professor of iMetallnrgv at the Ju'olo des Mines. 
Translated, with t'lie Author's sanction, witli an Appendix, bvL. D. B. 
Gordon, F. R. S. E., F. U. fcJ. Illustrated. Swo. . . .' $2.60 



HENRY CAREY BAIRD'S CATALOGUE. 11 

GUETTIER.— Metallic AUoys: 

Being a Practical Guide to their Chemical and Physical Properties, 
their Preparation, Composition, and Uses. Translated from the 
French of A. GrETTiER, Engineer and Director of Foundries, author 
of" La Fouderie en France," etc., etc. By A. A. Fesquet, Chemist 
and Engineer. In one volume, 12mo. . ' . . . . $3.00 

HARRIS. — Gas Superintendent's Pocket Companion. 

By Harris & Brother, Gas Meter Manufacturers, 1115 and 1117 
Cherry Street, Philadelphia. Full bound in pocket-book form $1,00 

Hats and Felting: 

A Practical Treatise on their Manufacture. By a Practical Hatter. 
Illustrated by Drawings of Machinery, etc. 8vo. . . . $1.25 

HOFMANN.— A Practical Treatise on the Manufac- 
ture of Paper in all its Branches. 

By Carl Hofmaxn. Late Superintendent of paper mills in Ger- 
many and the United States ; recently manager of the Public Ledger 
Paper Mills, near Elkton, Md. Illustrated by 110 wood engravings, 
and five large folding plates. In one volume, 4to., cloth; 398 
pages $15.00 

HUGHES. — American Miller and Millwright's Assist- 
ant. 

By Wm. Carter Hughes. A new edition. In one vol., 12mo. $1.50 

HURST.— A Hand-Book for Architectural Surveyors 
and others engaged in Building: 

Containing Formulae useful in Designing Builder's work, Table of 
Weights, of the materials used in Building, Memoranda connected 
with Builders' work, Mensuration, the Practice of Builders' Measure- 
ment, Contracts of Labor, Valuation of Property, Summary of the 
Practice in Dilapidation, etc., etc. By J. F. Hurst, C. E. ' Second 
edition, pocket-book form, full bound ' $2.00 

JERVIS.— Railway Property : 

A Treatise on the Construction and Management of Railways ; de- 
signed to afford useful knowledge, in the popular style, to the holders 
of' this class of property ; as well as Railway Managers, Officers, and 
Agents. Bv John B.'Jervis, late Chief Engineer of the Hudson 
River Railroad, Croton Aqueduct, etc. In one vol., 12mo., cloth $2.00 

JOHNSTON.— Instructions for the Analysis of Soils, 
Limestones, and Manures. 

By J. F. T\', J0H>-ST0N. 12mo 



12 



HENRY CAREY BAIRD'S CATALOGUE. 



KEENE.— A Hand-Book of Practical Gauging : 

For the Use of Beginners, to which is added, A Chapter on Distilla- 
tion, describing the j^rocess in operation at the Custom House for 
ascertaining the strength of wines. By James B. Keene, of H. M. 
Customs. 8vo. $1.25 

KELLEY.— Speeches, Addresses, and Letters on Iji- 
dustrial and Financial Questions. 
By Hon. William D. Kelley, M. C. In one volume, 544 pages, 
8vo $3.00 

KENTISH.— A Treatise on a Box of Instruments, 

And the Slide Rule ; with the Theory of Trigonometry and Loga- 
rithms, including Practical Geometry, Sui-veying, Measuring of Tim^ 
ber. Cask and Malt Gauging, Heights, and Distances. By Thomas 
Kentish. In one volume. 12ino $1.25 

KOBELL.—EBNI.— Mineralogy Simplified : 

A bhort Method of Determining and Classifying Minerals, by means 
of simple Chemical Experiments in the Wet Way. Translated from 
the last German Edition of F. VoN Kobell, with an Introduction to 
Blow-pipe Analysis and other additions. By Henri Erni, M. D., 
late Chief Chemist, Department of Agriculture, author of '' Coal Oil 
and Petroleum." In one volume, 12mo. .... $2.50 

LANDRIN.— A Treatise on Steel: 

Comprising its Theory, Metallurgy, Properties, Practical Working, 
and Use. By M. H. C. Landrin, Jr., Civil Engineer. Translated 
from the French, with Notes, by A. A. Fesquet, Chemist and Engi- 
neer. With an Appendix on the Bessemer and the Martin Processes 
for Manufacturing Steel, from the Report of Abram S. Hewitt, United 
States Commissioner to the Univei'sal Exposition, Paris, 1867. In one 
volume, 12mo. $3.00 



Mi 



LARKIN.^The Practical Brass 
Guide : 



and Iron Founder's 



A Concise Trea+ise on Brass Founding, Moulding, the Metals and their 
Alloys, etc. : to which are added Recent Improvements in the Manu- 
facture of Iron, Steel by the Bessemer Process, etc., etc. By James 
Lark in, late Conductor of the Brass Foundry Department in Rouny, 
Neafie & Co's. Ponn Works, Philadelphia. Fifth edition, revised, 
with Extensive additions. In one volume, 12mo. . . $2.25 



IiEAVITT.— Facts about Peat as an Article of Fuel : 

Witli Remarks ui)on its Origin and Conijxjsition, the Localities in 
which it is found, the ^Methods of Preparation and JManufaeturc. and 
the various Uses to which it is ai)plieable ; together with many other 
matters of Practical and Scientific Interest. To which is addeil a chap- 
ter on the Utilization of Coal Dust with Peat for the Proihictiou of an 
Exc(!lh!nt Fuel at Moderate Cost, s})ecially athipled for Steam Service. 
By T. il. Leavitt. Third edition. 12uio. . , , $1.75 



HENRY CAREY BAIRD'S CATALOGUE. 13 

liEROUX, C— A Practical Treatise on the Manufac- 
ture of Worsteds and Carded Yarns : 

Comprising Practical Mechanics, with Rules and Calculations applied 
to Spinning; Sorting, Cleaning, and Scouring Wools; the English 
and French methods of Combing, Drawing, and Spinning Worsteds 
and Manufacturing Carded Yarns. Translated from the French of 
Charles Leroux, Mechanical Engineer, and Superintendent of a 
Spinning Mill, by HoEATio Paine, M. D., and A. A. Fesquet, 
Chemist and Engineer. Illustrated by 12 large Plates. To which is 
added an Appendix, containing extracts from the Reports of the Inter- 
national Jury, and of the Artisans selected by the Committee appointed 
by the Council of the Society of Arts, London, on Woollen and Worsted 
Machinery and Fabrics, as exhibited in the Paris Universal Exposi- 
tion, 1867. 8vo., cloth $5.00 

LESLIE (Miss).— Complete Cookery: 

Directions for Cookery in its Various Branches. By Miss Leslie. 
60th thousand. Thoroughly revised, with the addition of New Re- 
ceipts. In one A^olume, 12mo,, cloth $1.50 

LESLIE (Miss).— Ladies' House Book: 
A Manual of Domestic Economy. 20th revised edition. 12mo., cloth. 

LESLIE (Miss).— Two Hundred Receipts in French. 
Cookery. 

Cloth, 12mo. 

LIEBER.— Assayer's Guide: 

Or, Practical Directions to Assayers, Miners, and Smelters, for the 
Tests and Assays, by Heat and by Wet Processes, for the Ores of .all 
the principal Metals, of Gold and Silver Coins and Alloys, and of 
Coal, etc. By Oscar M. Lieber. 12mo., cloth. . . $1.25 

LOTH.— The Practical Stair Builder : 

A Complete Treatise on the Art of Building Stairs and Hand-Rails, 
Designed for Carpenters, Builders, and Stair-Builders. Illustrated 
with Thirty Original Plates. By C. Edward Loth, Professional 
Stair-Builder. One large 4to. volume. .... $10.00 

LOVE.— The Art of Dyeing, Cleaning, Scouring, and 
Finishing, on the Most Approved English and 
French Methods: 

Being Practical Instructions in Dyeing Silks, Woollens, and Cottons, 
Feathers, Chips, Straw, etc. Scouring and Cleaning Bed and Window 
Curtains, Carpets, Rugs, etc. French and English Cleaning, any 
Color or Fabric of Silk, Satin, or Damask. By Thomas Love, a 
Working Dyer and Scourer. Second American Edition, to which are 
added Gieneral Instructions for the Use of Aniline Colors. In one 
volume, Svo., 343 pages. $5.00 



14 



HENRY CAREY BAIRD'S CATALOGUE. 



MAIN and BROWN.— Questions on Subjects Con- 
nected with the Marine Steam-Engine : 

And Examination Papers ; with Hints for their Solution. By Thomas 
J. Main, Professor of Mathematics, Royal Naval College, and Thomas 
Beown, Chief Engineer, R. N. 12mo., cloth. . . . $1.50 



MAIN and BROWN. 

meter : 



-The Indicator and Dynamo- 



With their Practical Applications to the Steam-Engine. By Thomas 
J. Main, M. A. F. R., Assistant Professor Royal Naval College, Ports- 
mouth, and Thomas Brown, Assoc. Inst. C. E., Chief Engineer, R. 
N., attached to the Royal Naval College. Illustrated. From the 
Fourth London Edition. 8vo. $1.50 

MAIN and BROWN.— The Marine Steam-Engine. 

By Thomas J. Main, F. R. ; Assistant S. Mathematical Professor at 
the Royal Naval College, Portsmouth, and Thomas Brown, Assoc. 
Inst. C. E., Chief Engineer R. N. Attached to the Royal Naval Col- 
lege. Authors of " Questions connected with the Marine Steam-En- 
gine," and the " Indicator and Dynamometer." With numerous Illus- 
trations. In one volume, 8vo. $5.00 

MARTIN.— Screw-Cutting Tables, for the Use of Me- 
chanical Engineers : 

Showing the Proper Arrangement of Wheels for Cutting the Threads 
of Screws of any required Pitch ; with a Table for Making the Uni- 
versal Gas-Pipe Thread and Taps. By W. A. Martin, Engineer. 
8vo 50 

Mechanics' (Amateur) Workshop: 

A treatise containing plain and concise directions for the manipula- 
tion of Wood and Metals, including Casting, Forging, Brazing, Sol- 
dering, and Carpentry. By the author of the " Lathe and its Uses." 
Third edition. Illustrated. 8vo $3.00 

MOLESWORTH.— Pocket-Book of Useful Formulae 
and Memoranda for Civil and Mechanical Engi- 
neers. 
By Guilford L. Molesworth, Member of the Institution of Civil 
Engineers, Chief Resident Engineer of the Ceylon Railway. Second 
American, from the Tenth London Edition. In one volume, full 
bound in pocket-book form $1.00 



NAPIER.— A System of Chemistry Applied to Dyeing. 

By Jamks Napier, F. C. S. A Now and Thoroughly Revised IMi- 
tion. Completely brought up to the present state of the Science, inclu- 
ding the Clieniistry of Coal Tar Colors, by A. A. Fksqukt, (^hcinist 
anci Engineer, With an Appendix on Dyoiiig and (^ilico Printing, as 
shown at the Universal Exposition, Paris, 1807. Illustrated. In one 
Volume, 8vo., 422 pages , ^.00 



HENRY CAREY BAIRD'S CATALOGUE. 15 

NAPIER.— Manual of Electro-Metallurgy : 

IiK-ludiiiL,^ the Application of the Art to Manufacturing Processes. By 
James >* ai'IKK. Fourth American, from the Fourth London edition, 
revised and enlarged. Illustrated by engravings. Inone vol., 8vo. $2.00 

NASON.— Table of Reactions for Qualitative Chemical 
Analysis. 
By Hexky B. Xason, Professor of Chemistry in the Rensselaer Poly- 
technic Institute, Troy, New York. Illustrated by Colors. 

NEWBERY.— Gleanings from Ornamental Art of 
every style : 
Drawn from Examples in the British, South Kensington, Indian, 
Crystal Palace, an(' ^ther Museums, the Exhibitions of 1851 and 18G2, 
and the best Engli^ii and Foreign works. In a series of one hundred 
exquisitely drawn Plates, containing many hundred examj^les. By 
ROBEET Newbeey. 4to $12.50 

NICHOLSON.— A Manual of the Art of Bookbinding : 

Containing full instructions in the different Branches of Forwarding, 
Gilding, and Finishing. Also, the Art of Marbling Book-edges and 
Paper. By James B. Nicholson. Illustrated. 12mo., cloth. $2.25 

NICHOLSON.— The Carpenter's New Guide: 

A Complete Book of Lines for Carpenters and Joiners. By Peter 
Nicholson. The -whole carefully and thoroughly revised by H. K. 
Davis, and containing numerous new and improved and original De- 
signs for Roofs, Domes, etc. By Samuel Sloan, Architect. Illus- 
trated by 80 plates. 4to. . . . ' . 

NORRIS.— A Hand-book for Locomotive Engineers 
and Machinists: 

Comprising the Proportions and Calculations for Constructing Loco- 
motives ; Manner of Setting Valves ; Tables of Squares, Cubes, Areas, 
etc., etc. By Septimus Noeeis, Civil and Mechanical Engineer. 
New edition. Illustrated. 12mo., cloth $1.50 

NYSTROM.— On Technological Education, and the 

Construction of Ships and Screw Propellers : 

For Naval and Marine Engineers. Bv John W. Nysteom, late Act< 

ing Chief Engineer, U. S. N. Second edition, revised with additional 

matter. Illustrated by seven engravings. 12mo. . . $1.50 

O'NEILL.— A Dictionary of Dyeing and Calico Print- 
ing: 

Containing a brief account of all the Substances and Processes in use 
in the Art of Dveing and Printing Textile Fabrics ; with Practical 
Receipts and Scientific Information. By Chaeles O'Neill, Ana- 
Ivtical Chemist ; Fellow of the Chemical Society of London ; Member 
of the Literarv and Philosophical Society of Manchester ; Author of 
" Chemistrv of Calico Printing and Dyeing." To which is added an 
Essay on Coal Tar Colors and their application to Dyeing and Calico 
Printing. Bv A. A. Fesquet, Chemist and Engineer. With an Ap- 
pendix on DVeing and Calico Printing, as shown at the Universal 
Exposition, Paris, 1867. In one volume, 8vo., 491 pages. . $5.00 



16 HENRY CAREY BAIRD'S CATALOGUE. 

ORTON.— Underground Treasures : 

How and Where to Find Them. A Key for the Ready Determination 

of all the Useful Minerals within the United States. By James 

\ Orton, a. M. Illustrated, 12mo , $1.50 

J O SB ORN.— American Mines and Mining: 

Theoretically and Practically Considered. By Prof. H. S. OSBORN. 
Illustrated by numerous engravings. 8vo. {In preparation.) 

^OSBORN.— The Metallurgy of Iron and Steel: 

Theoretical and Practical in all its Branches ; with special reference 
to American Materials and Processes. By H. S. Osborn, LL. D., 
Professor of Mining and Metallurgy in Lafayette College, Easton, 
Pennsylvania. Illustrated by numerous large folding plates and 
wood-engravings. 8vo. $17.60 

OVERMAN.— The Manufacture of Steel : 

Containing the Practice and Principles of Working and Making Steel. 
A Handbook for Blacksmiths and Workers in Steel and Iron, Wagon 
Makers, Die Sinkers, Cutlers, and Manufacturers of Files and Hard- 
ware, of Steel and Iron, and for Men of Science and Art. By Fred- 
erick Overman, Mining Engineer, Author of the " Manufacture of 
Iron," etc. A new, enlarged, and revised Edition. By A. A. Fesquet, 
Chemist and Engineer $1.50 

"^ OVERMAN.— The Moulder and Founder's Pocket 
Guide : 

A Treatise on Moulding and Founding in Green-sand, Dry-sand, Loam, 
and Cement ; the Moulding of Machine Frames, Mill-gear, Hollow- 
, ware, Ornaments, Trinkets, Bells, and Statues ; Description of Moulds 
for Iron, Bronze, Brass, and other Metals ; Plaster of Paris, Sulphur, 
Wax, and other articles commonly used in Casting ; the Construction 
of Melting Furnaces, the Melting and Founding of Metals ; the Com- 
position of Alloys and their Nature. With an Appendix containing 
Receipts for Alloys, Bronze, Varnishes and Colors for Castings; 'also. 
Tables on the Strength and other qualities of Cast Metals. By Fred- 
erick Overman, Mining Engineer, Author of " The Manufacture 
of Iron." With 42 Illustrations. 12mo $2.00 

Painter, Gilder, and Varnisher's Companion : 

Containing Rules and Regulations in everytliing relating to the Arts 
of Painting, Gilding, Varnishing, Glass-Staining, Graining, Marbling, 
Sign-Writing, Gilding on Glass,"and Coach Painting and Varnisliing; 
Tests for the Detection of Adulterations in Oils, Colors, etc. ; and a 
Statement of the Diseases to which Painters are jKH'uliarly liable, with 
the Simplest and Best Remedies. Sixteenth Edition. Revised, with 
an Appendix. Containing Colors and Coloring -Theoretical and 
Practical. (Comprising descriptions of a great variety of Ailditional 
Pigments, their (Qualities and Uses, to which are added, Drvers, and 
Modes and Operations of Painting, etc. Together with CKevreurs 
I*rinci])les of Harmony and Contrast of Colors. 12mo., cloth. $1.60 



HENRY CAREY BAIRD'S CATALOGUE. 17 

PALLETT.— The Miller's, Millwright's, and Engineer's 

Guide. 
By Henry Pallett. Illustrated. In one volume, 12uio. $3.00 

PERCY.— The Manufacture of Russian Sheet-Iron. 
By John Percy, M.P., F.R.S., Lecturer on Metalluru'v at the Royal 
School of Mines, and to The Advanced Class of Artillery Officers at 
the Royal Artillery Institution, "Woolwich; Author of" Metallurgy." 
With Illustrations. 8vo., paper. 50 cts. 

PERKINS.— Gas and Ventilation. 

Practical Treatise on Gas and Ventilation. With Special Relation to 
Illuniinatin!;, Heating, and Cooking by Gas. Including Scientific 
Helps to Engineer-students and others. With Illustrated Diagrams, 
By E. E. Perkins. 12mo., cloth i<l.2o 

PERKINS and STOWE.— A New Guide to the Sheet- 
iron and Boiler Plate Roller : 

Containing a Series nf Tables showing the Weight of Slabs and Piles 
to produce Boiler Plates, and of the AVeight of Piles and the Sizes of 
Bars to produce Sheet-iron; the Thickness of the Bar Gauge in 
decimals ; the Weiudit per foot, and the Thickness on the Bar or "Wire 
Gauge of the fractional ])arts of an inch ; the Weight jier sheet, and 
the Thickness on the Wire Gauge of Sheet-iron of various dimensions 
to weigh 112 lbs. per bundle; and the conversion of Short Weight 
into Long Weicrht, and Long Weiirht into Short. Estimated and col- 
lected by G. H. Perkins and J. G. Stowe $2.50 

PHILLIPS and DARLINGTON.— Records of Mining 
and Metallurgy; 
Or Facts and Memoi*anda for the use of the Mine Agent and Smelter. 
By J. Arthur Phillips, Mining Engineer, Graduate of the Imperial 
School of Mines, France, etc., and John Darlington. Illustrated 
by numerous engravings. In one volume, 12mo. . . $1.50 

PRO TEAUX.— Practical Guide for the Manufacture 
of Paper and Boards. 

By A. Proteaux, Civil Engineer, and Graduate of the School of Arts 
and Manufactures, and Director of Thiers' Pai)er Mill, Puy-de-Dome. 
With additions, by L. S. Le Normand. Translated from the French, 
^vith Notes, by Horatio Paine, A. B., M. D. To which is added a 
Chapter on the Manufiicture of Pa])er from Wood in the United 
States, by Henry T. Brown, of the " American Artisan." Illus- 
trated bv six plates, containing Drawings of Raw Materials, Maehi- 
nery, Plans of Paper-Mills, etc., etc. 8vo $10.00 

JIEGNAULT.— Elements of Chemistry. 
Bv M. V. Regnaui.t. Translated from the French by T. Forrest 
Betton, M. D., and edited, with Notes, by James C. Booth, Melter 
and Refiner U. S. Mint, and Wm. L. Fabe'r, Metallurgist and Mining 
Engineer. Illustrated by nearly 700 wood engravings. Comprising 
nearly 1500 pages. In two volumes, 8vo., cloth. . . . $7.50 



18 HENEY CAREY BAIRD'S CATALOGUE. 

REID,— A Practical Treatise on the Manufacture of 
Portland Cement : 
By Henry Reid, C. E. To which is added a Translation of M. A, 
Lipowitz's Work, describing a New Method adopted in Germany for 
Manufacturing that Cement, by W. F. Reid. Illustrated by plates 
and wood engravings. 8vo $7,20 

RIFFAULT, VERGNAUD, and TOUSSAINT.— A 
Practical Treatise on the Manufacture of Var- 
nishes. 
By M M. RiFFAULT, Vergnaud, and Toussaint. Revised and 
Edited by M. F. Malepeyre and Dr. Emil Winckler. Illustrated. 
In one volume, 8vo. {In preparation.) 

RIFFAULT, VERGNAUD, and TOUSSAINT.— A 
Practical Treatise on the Manufacture of Colors 
for Painting : 

Containing the best Formulae and the Processes the Newest and in 
most General Use. By M M. Riffault, Vergnaud, and Toussaint. 
Revised and Edited by M. F. Malepeyre and Dr. Emil Winckler. 
Translated from the French by A. A. Fesquet, Chemist and Engi- 
neer. Illustrated by Engravings. In one volume, 650 pages, 8vo. 

$7.50 

ROBINSON.— Explosions of Steam Boilers: 

How they are Caused, and how they may be Prevented. By J. R. 
Robinson, Steam Engineer. 12mo 

ROPER.— A Catechism' of High Pressure or Non- 
Condensing Steam-Engines : 

Including the Modelling, Constructing, Running, and ]S[anagement 
of Steam Engines and Steam Boilers. With Illustrations. By 
Stephen Roper, Engineer. Full bound tucks . . . $2.00 

ROSELEUR.— Galvanoplastic Manipulations : 
A Practical Guide for the Gold and Silver Electro-plater and the 
Galvanoplastic Operator. Translated from the French of ALFRED 
Roseleur, Chemist, Professor of the Galvanoplastic Art, Manufactu- 
rer of Chemicals, Gold and Silver Electro-plater. By A. A. Fesquet, 
Chemist and Engineer. Illustrated by over 127 Engravings on wood. 

8vo., 495 pages. ?7.50 

j^r"^'^ This Treatise is the fullest and by far the best on this subject ever 

published in the United States. 

SCHINZ.— Researches on the Action of the Blast 
Furnace. 

By CllAKLKS SciliNZ, Transhttcd from the Gonunn M-ith the si>0('ial 
jK-rinission of the Author by Wii.LiAM 11. Maw and MoKiTZ Mri.- 
Ll'Ml. With an A|)i)cndix writtt'u by the Antluir expressly for this 
edition. Illustrated by seven ])hites, containing 2S figures. In one 
volume, 12mo. 



*"r 



HENRY CAREY BAIRD'S CATALOGUE. 19 

SHAW.— Civil Architecture : 

Being a Coini)lete Theoretical and Practical System of Building, con- 
taining tlie Fundamental Principles of the Art. By Edward iSiiAW, 
Architect. To ^vluch is added a Treatise on Gothic Architecture, etc. 
By Thomas W. Silloway and George M. Harding, Architects. 
The Avhole illustrated by One Hundred and Two quarto plates finely 
engraved on copper. Eleventh Edition. 4to., cloth. . $10.00 

SHUNK.— A Practical Treatise on Railway Curves 
and Location, for Young Engineers. 
By William F. Shunk, Civil Engineer. 12mo. . . $2.00 

SLOAN. — American Houses : 

A variety of Original Designs for Rural Buildings. Illustrated by 26 
colored Engravings, with Descriptive References. By Samuel Sloan, 
Architect, author of the " Model Architect," etc., etc. 8vo. $1.50 

SMEATON.— Builder's Pocket Companion: 

Containing the Elements of Building, Surveying, and Architecture; 
with Practical Rules and Instructions connected with the subject. 
By A. C. Smeaton, Civil Engineer, etc. In one volume, 12mo. $1.50 

SMITH.— A Manual of Political Economy. 
By E, Peshine Smith. A new Edition, to Avhich is added a full 
Index. 12mo., cloth $1.25 

SMITH.— Parks and Pleasure Grounds: 

Or Practical Notes on Country Residences, Villas, Public Parks, and 
Gardens. By Charles H. J. Smith, Landscape Gardener and 
Garden Architect, etc., etc. 12mo. $2.25 

SMITH.— The Dyer's Instructor: 

Comprising Practical Instructions in the Art of Dyeing Silk, Cotton, 
Wool, and Worsted, and Woollen Goods : containing nearly 800 
Receipts. To which is added a Treatise on the Art of Padding ; and 
the Printing of Silk Warps, Skeins, and Handkerchiefs, and the 
various Mordants and Colors for the different styles of such work. 
By David Smith, Pattern Dyer. 12mo., cloth. . . . $3.00 

SMITH.— The Dyer's Instructor: 

Comprising Practical Instructions in the Art of Dyeing Silk, Cotton, 
Wool, and Worsted and Woollen Goods. Third Edition, with many 
additional Receipts for Dyeing the New Alkaline Blues and Night 
Greens, with Dyed Patterns ajfixed. 12mo., pp. 394, cloth. . $10.50 

STEWART.— The American System. 

Speeches on the Tariff Question, and on Internal Improvements, princi- 
pallv delivered in the Honse of Representatives of the United States. 
By Andrew Stewart, late M. C. from Pennsylvania. With a Portrait, 
and a Biographical Sketch. In one volume, 8vo., 407 pages. $3.00 



20 HENRY CAREY BAIRD'S CATALOGUE. 

STOKES. — Cabinet-maker's and Upliolsterer's Com- 
panion : 

Comprising the Rudiments and Principles of Cabinet-making and Up- 
holstery, with Familiar Instructions, illustrated by Examples for 
attaining a Proficiency in the Art of Drawing, as applicable to Cabi- 
net-work ; the Processes of Veneering, Inlaying, and Buhl-work ; the 
Art of Dyeing and Staining Wood, Bone, Tortoise Shell, etc. Direc- 
tions for Lackering, Japanning, and Varnishing ; to make French 
Polish; to prepare the Best Glues, Cements, and Compositions, and a 
number of Receipts particularly useful for workmen generally. By 
J. Stokes. In one volume, 12mo. With Illustrations. . $1.25 

Strength and other Properties of Metals: 

Reports of Experiments on the Strength and other Properties of Metals 
for Cannon. With a Description of the Machines for testing Metals, 
and of the Classification of Cannon in service. By Officers of the Ord- 
nance Department U. S. Army. By authority of the Secretary of War. 
Illustrated by 25 large steel plates.' In one volume, 4to. . $10.00 

SULLIVAN.— Protection to Native Industry. 
By Sir Edward Sullivan, Baronet, author of " Ten Chapters on 
Social Reforms." In one volume, 8vo $1.50 

Tables Showing the Weight of Round, Square, and 
Flat Bar Iron, Steel, etc., 
By Measurement. Cloth 63 

TAYLOR.— Statistics of Coal : 

Including jMineral Bituminous Substances employed in Arts and 
Manufactures; with their Geographical, Geological, and Commercial 
Distribution and Amount of Production and Consumption on the 
American Continent. With Incidental Statistics of the Iron Manu- 
facture. By R. C. Taylor. Second edition, revised by S. S. IIal- 
DEMAN. Illustrated by five Max)s and many wood engravings. 8vo., 
clotli $10.00 

TEMPLETON.— The Practical Examinator on Steam 

and the Steam-Engine : 

With Instructive References relative thereto, arranged for the I'sc of 

Engineers, Students, and others. By Wm. Templeton, Engineer. 

12mo ^ $1.25 

THOMAS.— The Modern Practice of Photography. 

By R. W. Thomas, F.C.S. 8vo., cloth 75 

THOMSON.— Freight Charges Calculator. 

By Andrew Thomson, Freight Agent. 2}mo. . . . $1.25 

TURNING: Specimens of Fancy Turning Executed 

on the Hand or Foot Lathe: 

With (ieometric, Oval, and FiCeoiitric Chucks, and Elliptical (""ntliiig 

Frame. By an Aniatenr. Illustrated by 30 exquisite Photographs. 

4tO'. $3.00 



IIEXRY CAREY BAIRD'S CATALOGUE. 21 

Turner's (The) Companion: 

Containing Instructions in Concentric, Elliptic, and Eccentric Turn- 
ing: also various Plates of Chucks, Tools, and Instruments ; and Di- 
rections for using the Eccentric Cutter, Drill, Vertical Cutter, and 
Circular llest ; Avith Patterns and Instructions for working them. A 
new edition in one volume, 12mo. ^l.oO 

URBIlsr.— BRULL.— A Practical Guide for Puddling 
Iron and Steel. 
By Ed. Ukdix, Engineer of Arts and Manufactures. A Prize Essay 
read before the Association of Engineers, Graduate of the tSciiooi of 
Mines, of Liege, Delgium, at the Meeting of 18G5-d. To which is added 
A CoMPArasox of the Hesisting Peoperties of Iron and Steel. 
By A. Brull. Translated from the French by A. A. Fesquet, Che- 
mist and Engineer. In one volume, Svo $1.00 

VAILE.— Galvanized Iron Cornice- Worker's Manual.* 

Containing Instructions in Laying out the Different Mitres, and Ma- 
king Patterns for all kinds of Plain and Circular Work. Also, Tables 
of Weights, x^Lreas and Circumferences of Circles, and other Mattet 
calculated to Benefit the Trade. By Charles A. Vaile, Sujierin- 
tendent " Richmond Cornice Vv'orks," Richmond, Indiana. Illustra- 
ted by 21 Plates. In one volume, 4to ^5.00 

VILLE.— The School of Chemical Manures : 

Or, Elementary Principles in the Use of Fertilizing Agents. From the 
French of M. George Yille, by A. A. Fesquet, Chemist and Engi- 
neer. With Illustrations. In one volume, 12 mo. . . i^l.25 

VOGDES.— The Architect's and Builder's Pocket Com- 
panion and Price Book: 

Consisting of a Short but Comprehensive Epitome of Decimals, Duo- 
decimals, Geometry and Mensuration ; with Tables of U. S. Measures, 
Sizes, Weights, Strengths, etc., of Iron, Wood, Stone, and various 
other Materials, Quantities of Materials in Given Sizes, and Dimen- 
sions of Wood, Brick, and Stone; and a full and complete Bill of 
Prices for Carpenter's Work; also, Rules for Computing and Valuing 
Brick and Brick AVork, Stone Work, Painting, Plastering, etc. By 
Frank W. Vogdes, Architect. Illustrated. Full bound in pocket- 
book form $2.00 

Bound in cloth. 1-50 

WARN.— The Sheet-Metal Worker's Instructor: 

For Zinc, Sheet-Iron, Copper, and Tin-Plate Workers, etc. Contain- 
ing a selection of Geometrical Problems ; also. Practical and Simple 
Rules for describing the various Patterns required in the ditierent 
branches of the above Trades. By Reuben H. Warn, Practical Tin- 
plate Worker. To which is added an Appendix, containing Instruc- 
tions for Boiler Making, Mensuration of Surfaces and Solids, Rules for 
Calculating the Weiojhts of different Figures of Iron and Steel, Tables 
of the Weights of Iron, Steel, etc. Illustrated by 32 Plates and 37 
Wood Engravings. 8vo. $3.00 



22 HENRY CAREY BAIRD'S CATALOGUE. 

WATSON.— A Manual of the Hand-Lathe: 

Comprising Concise Directions for working Metals of all kinds, Ivory, 
Bone and Precious AVoods ; Dyeing, Coloring, and French Polishing; 
Inhxying by Veneers, and various methods practised to produce Elabo- 
rate work with Dispatch, and at Small Expense. By Egbert P. 
Watson, late of '' The Scientific American," Author of " The Modern 
Practice of American Machinists and Engineers." Illustrated by 78 
Engravings 81.50 

^WATSON.— The Modern Practice of American Ma- 
chinists and Engineers: 

Including the Construction, Application, and Use of Drills, Lathe 1 

Tools, Cutters for Boring Cylinders, and Hollow Work Generally, 

Avith the most Economical Speed for the same ; the Results verified by 

Actual Practice at the Lathe, the Vice, and on the Floor. Together 

with Workshop Management, Economy of Manufacture, the Steam- 

Engiue, Boilers, Gears, Belting, etc., etc. By Egbert P. Watson, 

late of the " Scientific American." Illustrated by 86 Engravings. In 

one volume, 12mo S2.50 

WATSON.— The Theory and Practice of the Art of J 

Weaving by Hand and Power : I 

With Calculations and Tables for the use of those connected Avith the 

Trade. By .John Watson, Manufacturer and Practical Machine 1 

Maker. Illustrated by large Drawings of the best Power Looms. 

8vo. $7.50 

WEATHERLY.— Treatise on the Art of Boiling Su- 
gar, Crystallizing, Lozenge-making, Comfits, Qum ^ 
Goods. 
12mo $2.00 

"WILL.— Tables for Qualitative Chemical Analysis. 

By Professor Heinrich Will, of Giessen, Germany. Seventli edi- 
tion. Translated by Charles F. Himes, Ph. D., Professor of Natu- 
ral Science, Dickinson College, Carlisle, Pa. . . . !?1.50 

WILLIAMS.— On Heat and Steam : 

Embracing New Views of Vaporization, Condensation, and Explosions. 
By Charles Wye Williams, A. I. C. E. Illustrated. 8vo. $3.50 

WOHLER.— A Hand-Book of Mineral Analysis. 

By F. Wohler, Professor of Chemistry in the Universitv of Giittin- 
gen. Edited by Henry B. Nason, Professor of Chemistry in the 
Kensselaer Polytechnic Institute, Troy, NewYork. Illustrated. In 
one volume, 12mo ! . . . ^3 00 

WORSSAM.— On Mechanical Saws: 

J-'rom the Transactions of tiie Society of Engineers, 1869. By S. AV. 
WoitSSAM, Jr. Illustrated by 18 large ])lutes. 8vo. . . $2.ti{} 



^ 



HEXRY CAREY BAIRD'S CATALOGUE. 23 



KEOENT ADDITIONS TO OUK LIST. 



AUERBACH. — Anthracen : Its Constitution, Properties, Man- 
ufacture, and Derivatives, including Artificial Alizarin, An- 
thrapurpurin, with their applications in Dyeing and Printing. 

Bv G. AUEKUACH. Translated and edited by Wm. Ceookes, F. It. S. 
8vo. .>.j.00 

BECKETT.— Treatise on Clocks, Watches and Bells. 
By Sir Edml'XD Beckett, Bart. Illustrated. 12mo. . $1.75 

BARLOW.— The History and Principles of Weaving, by Hand 
and by Power. 

Several Hundred Illustrations. 8vo $10.00 

BOURNE. — Recent Improvements in the Steam Engine. 

By John Bourne, C. E. Illustrated. l6mo '$1.50 

CLARK. — Fuel : Its Combustion and Economy. 

By D. KiNNEAR Clark, C. E. 144 Engravings. 12mo. . 31-50 
CRISTIANL— Perfumery and Kindred Arts. 

By R. S. Ceistiani. Svo. $5.00 

COLLENS.— The Eden of Labor, or the Christian Utopia. 

12mo. Paper, $1.00; Cloth, $1.25 

CUPPER.— The Universal Stair Builder. 

Illustrated by 29 plates. 4to. ...... $2.50 

COOLEY. — A Complete Practical Treatise on Perfumery, 

By A. J. CoOLEY. 12mo $1.50 

DAVIDSON.— A Practical Manual of House Painting, Grain- 
ing, Marbling and Sign Writing : 

"With 9 Colored. Illustrations of Woods and Marbles, and many "Wood 
Engravings. 12mo. ' $3.00 

EDWARDS.— A Catechism of the Marine Steam Engine. 
By Emory Edwards. Illustrated. 12mo. . . . $2.00 

HASERICK.— The Secrets of -he Art of Dyeing Wool, Cotton, 
and Linen : 

Inc-luding Bleaching and Coloring Wool and Cotton Hosiery and 
Random Yarns. By E. C. Ha.serick. Illustrated by 323 Dyed Pat- 
terns of the Yarns or Fabrics. Svo ' $25. UO 

HENRY.— The Early and Later History of Petroleum. 

By J. T. He>'RY. Illustrated. 8vo $4.50 



24 RENPwY CAREY BAIED'S CATALOGUE. 

KELLOGG.— A New Monetary System. 
By Ed. Kellogg. Fifth Edition. Edited by Maey Kellogg 
Putnam. 12ruo. Paper, §1.00; Cloth, .... $1.50 

KEMLO.— Watch Repairer's Hand-Book. 
Illustrated. 12mo. $1.25 

MORRIS. — Easy Rules for the Measurement of Earthworks by 
means of the Prismoidal Formula. 

By Elwood Morris, C. E. 8vo. $1.50 

McCULLOCH.— Distillation, Brewing and Malting. 

By J. C. McCuLLoeii. 12mo $1.00 

NEVILLE.— Hydraulic Tables, Co-Efficients, and Formulae 
for Finding the Discharge of Water from Orifices, Notches, 
Weirs, Pipes, and Rivers. 
Illustrated. 12nio ' . . . $5.00 

NICOLLS.— The Railway Builder. 

A Hand-book for Estimating the Probable Cost of American Railway 
Constrnction and Equipment. By Wm. J. NiCOLLS, C. E. Pocket- 
book Form $2.00 

NORMANDY.—The Commercial Hand-book of Chemical 
Analysis. 
By II. M. NoAD, Pb. D. 12mo $5.00 

PROCTOR.— A Pocket-Book of Useful Tables and Formulae 
for Marine Engineers. 
By Frank Proctor. Pocket-book Form. . . . $2.00 

ROSE.— The Complete Practical Machinist : 
Embracing Lathe Work, A^ise Work, Drills and Drilling, Taps and 
Dies, Hardening and Tem])ering, the Making and Use ot Tools, etc., 
etc. By Josinr^A Kose. 130 Illustrations. 12mo. . . $2.50 

SLOAN. — Homestead Architecture. 

By Samuel Sloan, Architect. 200 Engravings. 8vo. . $3.50 

SYME. — Outlines of an Industrial Science. 
By David Syme. 12mo $2.0(? 

WARE.— The Coachmaker's Illustrated Hand-Book. 

Fully Illnstiated. ,Svo $3.00 

WIGHTWICK.— Hints to Young Architects. 

Numerous Wood Cuts. 12nu) $2.00 

WILSON.— First Principles of Political Economy. 

12mo $1.50 

WILSON.— A Treatise on Steam Boilers, their Strength, Con- 
struction, and Economical Working. 
By Hour. Wilson. Jllustratod. 12mo $2.50 









